Method for controlling cutting member actuation for powered surgical stapler

ABSTRACT

A method is provided for operating a powered surgical stapler having a motor unit, a controller. and a stapling assembly having a closure member, a staple driver member, and a knife member. The controller receives a user input that indicates a tissue gap to be defined by the stapling assembly in a closed state. Based on the user input, the controller controls the motor unit to actuate the closure member to transition the stapling assembly to the closed state to define the tissue gap and clamp tissue therein. The controller then controls the motor unit to actuate the staple driver member to drive staples into the clamped tissue. In response to determining that the staple driver member has reached a predetermined longitudinal position, the controller controls the motor unit to initiate actuation of the knife member to cut the clamped tissue.

BACKGROUND

In some surgical procedures (e.g., colorectal, bariatric, thoracic,etc.), portions of a patient's digestive tract (e.g., thegastrointestinal tract and/or esophagus, etc.) may be cut and removed toeliminate undesirable tissue or for other reasons. Once the tissue isremoved, the remaining portions of the digestive tract may be coupledtogether in an end-to-end anastomosis, an end-to-side anastomosis, or aside-to-side anastomosis. The anastomosis may provide a substantiallyunobstructed flow path from one portion of the digestive tract to theother portion of the digestive tract, without also providing any kind ofleaking at the site of the anastomosis.

One example of an instrument that may be used to provide an anastomosisis a circular stapler. Some such staplers are operable to clamp down onlayers of tissue, cut through the clamped layers of tissue, and drivestaples through the clamped layers of tissue to substantially seal thelayers of tissue together near the severed ends of the tissue layers,thereby joining the two severed ends of the anatomical lumen together.The circular stapler may be configured to sever the tissue and seal thetissue substantially simultaneously. For instance, the circular staplermay sever excess tissue that is interior to an annular array of staplesat an anastomosis, to provide a substantially smooth transition betweenthe anatomical lumen sections that are joined at the anastomosis.Circular staplers may be used in open procedures or in endoscopicprocedures. In some instances, a portion of the circular stapler isinserted through a patient's naturally occurring orifice.

Examples of circular staplers are described in U.S. Pat. No. 5,205,459,entitled “Surgical Anastomosis Stapling Instrument,” issued Apr. 27,1993; U.S. Pat. No. 5,271,544, entitled “Surgical Anastomosis StaplingInstrument,” issued Dec. 21, 1993; U.S. Pat. No. 5,275,322, entitled“Surgical Anastomosis Stapling Instrument,” issued Jan. 4, 1994; U.S.Pat. No. 5,285,945, entitled “Surgical Anastomosis Stapling Instrument,”issued Feb. 15, 1994; U.S. Pat. No. 5,292,053, entitled “SurgicalAnastomosis Stapling Instrument,” issued Mar. 8, 1994; U.S. Pat. No.5,333,773, entitled “Surgical Anastomosis Stapling Instrument,” issuedAug. 2, 1994; U.S. Pat. No. 5,350,104, entitled “Surgical AnastomosisStapling Instrument,” issued Sep. 27, 1994; and U.S. Pat. No. 5,533,661,entitled “Surgical Anastomosis Stapling Instrument,” issued Jul. 9,1996; and U.S. Pat. No. 8,910,847, entitled “Low Cost Anvil Assembly fora Circular Stapler,” issued Dec. 16, 2014. The disclosure of each of theabove-cited U.S. Patents is incorporated by reference herein.

Some circular staplers may include a motorized actuation mechanism.Examples of circular staplers with motorized actuation mechanisms aredescribed in U.S. Pub. No. 2015/0083772, entitled “Surgical Stapler withRotary Cam Drive and Return,” published Mar. 26, 2015; U.S. Pub. No.2015/0083773, entitled “Surgical Stapling Instrument with Drive AssemblyHaving Toggle Features,” published Mar. 26, 2015; U.S. Pub. No.2015/0083774, entitled “Control Features for Motorized Surgical StaplingInstrument,” published Mar. 26, 2015; and U.S. Pub. No. 2015/0083775,entitled “Surgical Stapler with Rotary Cam Drive,” published Mar. 26,2015. The disclosure of each of the above-cited U.S. Patent Publicationsis incorporated by reference herein.

While various kinds of surgical stapling instruments and associatedcomponents have been made and used, it is believed that no one prior tothe inventor(s) has made or used the invention described in the appendedclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

While the specification concludes with claims which particularly pointout and distinctly claim this technology, it is believed this technologywill be better understood from the following description of certainexamples taken in conjunction with the accompanying drawings, in whichlike reference numerals identify the same elements and in which:

FIG. 1 depicts a perspective view of an exemplary circular surgicalstapler;

FIG. 2 depicts a perspective view of the circular stapler of FIG. 1,with a battery pack removed from a handle assembly and an anvil removedfrom a stapling head assembly;

FIG. 3 depicts a perspective view of the anvil of the circular staplerof FIG. 1;

FIG. 4 depicts a perspective view of the stapling head assembly of thecircular stapler of FIG. 1;

FIG. 5 depicts an exploded perspective view of the stapling headassembly of FIG. 4;

FIG. 6 depicts an exploded perspective view of the circular stapler ofFIG. 1, with portions of the shaft assembly shown separated from eachother;

FIG. 7A depicts a cross-sectional side view of the anvil of FIG. 3positioned within a first section of a digestive tract and the staplinghead assembly of FIG. 4 positioned in a second section of the digestivetract, with the anvil separated from the stapling head assembly;

FIG. 7B depicts a cross-sectional side view of the anvil of FIG. 3positioned within the first section of the digestive tract and thestapling head assembly of FIG. 4 positioned in the second section of thedigestive tract, with the anvil secured to the stapling head assembly;

FIG. 7C depicts a cross-sectional side view of the anvil of FIG. 3positioned within the first section of the digestive tract and thestapling head assembly of FIG. 4 positioned in the second section of thedigestive tract, with the anvil retracted toward the stapling headassembly to thereby clamp tissue between the anvil and the stapling headassembly;

FIG. 7D depicts a cross-sectional side view of the anvil of FIG. 3positioned within the first section of the digestive tract and thestapling head assembly of FIG. 4 positioned in the second section of thedigestive tract, with the stapling head assembly actuated to sever andstaple the clamped tissue;

FIG. 7E depicts a cross-sectional side view of the first and secondsections of the digestive tract of FIG. 7A joined together at anend-to-end anastomosis;

FIG. 8 depicts a perspective view of a user interface feature of thehandle assembly of the circular stapler of FIG. 1;

FIG. 9 depicts a perspective view of another exemplary circular surgicalstapler;

FIG. 10 depicts a schematic view of the circular stapler of FIG. 9,including a control system of the circular surgical stapler;

FIG. 11 depicts a diagrammatic view of an exemplary method forcontrolling the circular surgical stapler of FIG. 9 via the controlsystem of FIG. 10;

FIG. 12 depicts a diagrammatic view of an exemplary method forcalibrating actuation strokes of moveable members of the circularstapler of FIG. 9 by adjusting actuation algorithms executed by thecontrol system of FIG. 10;

FIG. 13A depicts a schematic side sectional view of the stapling headassembly and anvil of the circular surgical stapler of FIG. 9, showingthe anvil in a fully open position relative to the stapling headassembly;

FIG. 13B depicts a schematic side cross-sectional view of the staplinghead assembly and anvil of the circular surgical stapler of FIG. 9,showing the anvil in a partially closed position relative to thestapling head assembly;

FIG. 13C depicts a schematic side cross-sectional view of the staplinghead assembly and anvil of the circular surgical stapler of FIG. 9,showing the anvil in a fully closed position against the stapling headassembly;

FIG. 14 depicts a schematic side cross-sectional view of the stapleassembly and anvil of the circular surgical stapler of FIG. 9, showingthe anvil in a fully closed position against a staple retainer of thestapling head assembly;

FIG. 15 depicts a line graph showing longitudinal displacement of theanvil of the circular surgical stapler of FIG. 9 from a fully openposition to a fully closed position and back to the fully open position,showing calibration of the anvil stroke after closure and beforereopening;

FIG. 16 depicts a schematic view of a graphical indicator of a userinterface feature of the circular surgical stapler of FIG. 9, showingexemplary first and second tissue gap settings for the anvil;

FIG. 17A depicts a schematic side view of the stapling head assembly andanvil of the circular surgical stapler of FIG. 9, showing the anvilpositioned to define a first, larger tissue gap corresponding to thefirst tissue gap setting of FIG. 16;

FIG. 17B depicts a schematic side view of the stapling head assembly andanvil of the circular surgical stapler of FIG. 9, showing the anvilpositioned to define a second, smaller tissue gap corresponding to thesecond tissue gap setting of FIG. 16;

FIG. 18 depicts a schematic side elevational view of the stapling headassembly and anvil of the circular surgical stapler of FIG. 9, showingside portions cutaway to reveal a staple driver and a correspondingstaple housed within a respective staple opening of the stapling headassembly, showing the staple driver and staple in a fully recessedposition;

FIG. 19A depicts a side elevational view of the staple driver and stapleof FIG. 18, showing the staple driver and staple in the fully recessedproximal position;

FIG. 19B depicts a side elevational view of the staple driver and stapleof FIG. 18, showing the staple driver and staple in a partially extendedintermediate position in which an upper end of the staple driver and acrown of the staple are positioned at a deck surface of the staplinghead assembly and staple;

FIG. 19C depicts a side elevational view of the staple driver and stapleof FIG. 18, showing the staple driver and staple in a fully extendeddistal position in which legs of the staple are fully formed by theanvil;

FIG. 20 depicts a line graph showing exemplary relationships betweenoperational elements of the circular surgical stapler of FIG. 9 overtime, including anvil displacement, knife displacement, and firing loadon the motor unit; and

FIG. 21 depicts a line graph showing firing loads over time for thecircular surgical stapler of FIG. 9 in accordance with two differentfiring algorithms.

The drawings are not intended to be limiting in any way, and it iscontemplated that various embodiments of the technology may be carriedout in a variety of other ways, including those not necessarily depictedin the drawings. The accompanying drawings incorporated in and forming apart of the specification illustrate several aspects of the presenttechnology, and together with the description serve to explain theprinciples of the technology; it being understood, however, that thistechnology is not limited to the precise arrangements shown.

DETAILED DESCRIPTION

The following description of certain examples of the technology shouldnot be used to limit its scope. Other examples, features, aspects,embodiments, and advantages of the technology will become apparent tothose skilled in the art from the following description, which is by wayof illustration, one of the best modes contemplated for carrying out thetechnology. As will be realized, the technology described herein iscapable of other different and obvious aspects, all without departingfrom the technology. Accordingly, the drawings and descriptions shouldbe regarded as illustrative in nature and not restrictive.

For clarity of disclosure, the terms “proximal” and “distal” are definedherein relative to a surgeon, or other operator, grasping a surgicalinstrument having a distal surgical end effector. The term “proximal”refers to the position of an element arranged closer to the surgeon, andthe term “distal” refers to the position of an element arranged closerto the surgical end effector of the surgical instrument and further awayfrom the surgeon. Moreover, to the extent that spatial terms such as“top,” “bottom,” “upper,” “lower,” “vertical,” “horizontal,” or the likeare used herein with reference to the drawings, it will be appreciatedthat such terms are used for exemplary description purposes only and arenot intended to be limiting or absolute. In that regard, it will beunderstood that surgical instruments such as those disclosed herein maybe used in a variety of orientations and positions not limited to thoseshown and described herein.

I. Overview of Exemplary Circular Surgical Stapling Instrument

FIGS. 1-2 depict an exemplary circular surgical stapling instrument (10)that may be used to provide an end-to-end, side-to-side, or end-to-sideanastomosis between two sections of an anatomical lumen such as aportion of a patient's digestive tract. Instrument (10) of this exampleincludes a body assembly (e.g. a handle assembly (100)), a shaftassembly (200) extending distally from handle assembly (100), a staplinghead assembly (300) at a distal end of shaft assembly (200), and ananvil (400) configured to releasably couple and cooperate with staplinghead assembly (300) to clamp, staple, and cut tissue. Instrument (10)further includes a removable battery pack (120) operable to provideelectrical power to a motor (160) housed within handle assembly (100),as will be described in greater detail below.

Shaft assembly (200) extends distally from handle assembly (100) andincludes a preformed bend. In some versions, the preformed bend isconfigured to facilitate positioning of stapling head assembly (300)within a patient's colon. Various suitable bend angles or radii that maybe used will be apparent to those of ordinary skill in the art in viewof the teachings herein. In some other versions, shaft assembly (200) isstraight, such that shaft assembly (200) lacks a preformed bend. Variousexemplary components that may be incorporated into shaft assembly (200)will be described in greater detail below.

Stapling head assembly (300) is located at the distal end of shaftassembly (200). As shown in FIGS. 1-2 and as will be described ingreater detail below, anvil (400) is configured to removably couple withshaft assembly (200), adjacent to stapling head assembly (300). As willalso be described in greater detail below, anvil (400) and stapling headassembly (300) are configured to cooperate to manipulate tissue in threeways, including clamping the tissue, cutting the tissue, and staplingthe tissue. A knob (130) at the proximal end of handle assembly (100) isrotatable relative to casing (110) to provide precise clamping of thetissue between anvil (400) and stapling head assembly (300). When asafety trigger (140) of handle assembly (100) is pivoted away from afiring trigger (150) of handle assembly (100), firing trigger (150) maybe actuated to thereby provide cutting and stapling of the tissue.

A. Exemplary Anvil

As best seen in FIG. 3, anvil (400) of the present example comprises ahead (410) and a shank (420). Head (410) includes a proximal surface(412) that defines a plurality of staple forming pockets (414). Stapleforming pockets (414) are arranged in two concentric annular arrays inthe present example. In some other versions, staple forming pockets(414) are arranged in three or more concentric annular arrays. Stapleforming pockets (414) are configured to deform staples as the staplesare driven into staple forming pockets (414). For instance, each stapleforming pocket (414) may deform a generally “U” shaped staple into a “B”shape as is known in the art. Proximal surface (412) terminates at aninner edge (416), which defines an outer boundary of an annular recess(418) surrounding shank (420).

Shank (420) defines a bore (422) and includes a pair of pivoting latchmembers (430). Latch members (430) are positioned within bore (422) suchthat distal ends (434) are positioned at the proximal ends of lateralopenings (424), which are formed through the sidewall of shank (420).Lateral openings (424) thus provide clearance for distal ends (434) andlatch shelves (436) to deflect radially outwardly from the longitudinalaxis defined by shank (420). However, latch members (430) are configuredto resiliently bias distal ends (434) and latch shelves (436) to pivotradially inwardly toward the longitudinal axis defined by shank (420).Latch members (430) thus act as retaining clips. This allows anvil (400)to be removably secured to an actuatable closure member in the form of atrocar (330) of stapling head assembly (300), as will be described ingreater detail below. It should be understood, however, that latchmembers (436) are merely optional. Anvil (400) may be removably securedto trocar (330) using any other suitable components, features, ortechniques.

B. Exemplary Stapling Head Assembly

As best seen in FIGS. 4 and 5, stapling head assembly (300) of thepresent example is coupled to a distal end of shaft assembly (200) andcomprises a body member (310) and a staple driver member (350) slidablyhoused therein. Body member (310) includes a distally extendingcylindraceous inner core member (312). Body member (310) is fixedlysecured to an outer sheath (210) of shaft assembly (200), and bodymember (310) and outer sheath (210) thus serve together as a mechanicalground for stapling head assembly (300). In some versions, stapling headassembly (300) may be configured to releasably couple with the distalend of shaft assembly (200), for example as disclosed in U.S. Pat. No.9,597,081, entitled “Motor Driven Rotary Input Circular Stapler withModular End Effector,” issued Mar. 21, 2017, the disclosure of which isincorporated by reference herein.

Trocar (330) is positioned coaxially within inner core member (312) ofbody member (310). As will be described in greater detail below, trocar(330) is operable to translate distally and proximally relative to bodymember (310) in response to rotation of knob (130) relative to casing(110) of handle assembly (100). Trocar (330) comprises a shaft (332) anda head (334). Head (334) includes a pointed tip (336) and an inwardlyextending proximal surface (338). Shaft (332) thus provides a reducedouter diameter just proximal to head (334), with surface (338) providinga transition between that reduced outer diameter of shaft (332) and theouter diameter of head (334). While tip (336) is pointed in the presentexample, tip (336) is not sharp. Tip (336) will thus not easily causetrauma to tissue due to inadvertent contact with tissue. Head (334) andthe distal portion of shaft (332) are configured for insertion in bore(422) of anvil (400). Proximal surface (338) and latch shelves (436)have complementary positions and configurations such that latch shelves(436) engage proximal surface (338) when shank (420) of anvil (400) isfully seated on trocar (330). Anvil (400) is thus secured to trocar(330) through a snap fit provided by latch members (430).

Staple driver member (350) is operable to actuate longitudinally withinbody member (310) in response to activation of motor (160) as will bedescribed in greater detail below. Staple driver member (350) of thepresent example includes two distally presented concentric annulararrays of staple drivers (352). Staple drivers (352) are arranged tocorrespond with the arrangement of staple forming pockets (414) of anvil(400). Thus, each staple driver (352) is configured to drive acorresponding staple into a corresponding staple forming pocket (414)when stapling head assembly (300) is actuated. It should be understoodthat the arrangements of staple drivers (352) and staple forming pockets(414) shown herein may be modified in any suitable manner, provided thatstaple drivers (352) and staple forming pockets (414) are configured toalign with one another to provide proper formation of staples. Stapledriver member (350) also defines a bore (354) that is configured tocoaxially receive core member (312) of body member (310). An annulararray of studs (356) project distally from a distally presented surfacesurrounding bore (354).

A cylindraceous knife member (340) is coaxially positioned within stapledriver member (350). Knife member (340) includes a distally presented,sharp circular cutting edge (342). Knife member (340) is sized such thatknife member (340) defines an outer diameter that is smaller than thediameter defined by the inner annular array of staple drivers (352).Knife member (340) also defines an opening that is configured tocoaxially receive core member (312) of body member (310). An annulararray of openings (346) formed in knife member (340) is configured tocomplement the annular array of studs (356) of staple driver member(350), such that knife member (340) is fixedly secured to staple drivermember (350) via studs (356) and openings (346). By way of example only,studs (356) may be heat staked to knife member (340) using techniquesknown in the art. Other suitable structural relationships between knifemember (340) and stapler driver member (350) will be apparent to thoseof ordinary skill in the art in view of the teachings herein.

A deck member (320) is fixedly secured to a distal end of body member(310). Deck member (320) includes a distally presented deck surface(322) defining two concentric annular arrays of staple openings (324).Staple openings (324) are arranged to correspond with the arrangement ofstaple drivers (352) and staple forming pockets (414) described above.Thus, each staple opening (324) is configured to provide a path for acorresponding staple driver (352) to drive a corresponding staplethrough deck member (320) and into a corresponding staple forming pocket(414) when stapling head assembly (300) is actuated. It should beunderstood that the arrangement of staple openings (324) may be modifiedto correspond with the arrangement of drivers (352) and staple formingpockets (414) described above. It should also be understood that variousstructures and techniques may be used to contain staples within staplinghead assembly (300) before stapling head assembly (300) is actuated.Such structures and techniques that are used to contain staples withinstapling head assembly (300) may prevent the staples from inadvertentlyfalling out through staple openings (324) before stapling head assembly(300) is actuated. Various suitable forms that such structures andtechniques may take will be apparent to those of ordinary skill in theart in view of the teachings herein.

As best seen in FIG. 9, deck member (320) defines an inner diameter thatis just slightly larger than the outer diameter defined by knife member(340). Deck member (320) is thus configured to allow knife member (340)to translate distally to a point where cutting edge (342) is distal todeck surface (322).

In some versions of instrument (10) it may desirable to provideinstrument (10) with features that are configured to indicate properand/or improper attachment of anvil (400) to trocar (330) of staplinghead assembly (300). For instance, if anvil (400) is not properlyattached to trocar (330), an operator may receive audible and/or tactilefeedback indicating improper attachment. Additionally, if anvil (400) isproperly attached to trocar (330), an operator may receive audible,tactile, and/or visible feedback indicating proper attachment. Inaddition, or in the alternative, features may be configured to preventfiring of stapling head assembly (300) unless anvil (400) is properlyattached to trocar (330). For instance, if anvil (400) is not properlyattached to trocar (330), stapling head assembly (300) may be preventedfrom firing. If anvil (400) is properly attached to trocar (330), firingof stapling head assembly (300) may be enabled. Such features mayinclude various types of visual indicia, sensors, switches, and thelike. By way of example only, such features may include those of thetype disclosed in U.S. Pat. No. 10,307,157, entitled “Surgical Staplerwith Anvil Seating Detection,” issued Jun. 4, 2019, and U.S. Pub. No.2017/0258471, entitled “Methods and Systems for Performing CircularStapling,” published Sep. 14, 2017, the disclosures of which areincorporated by reference herein.

C. Exemplary Shaft Assembly

FIG. 6 shows various components of shaft assembly (200), which couplescomponents of stapling head assembly (300) with components of handleassembly (100). In particular, and as noted above, shaft assembly (200)includes an outer sheath (210) that extends between handle assembly(100) and body member (310). In the present example, outer sheath (210)is rigid and includes a preformed curved section as noted above.

Shaft assembly (200) further includes a trocar actuation rod (220) and atrocar actuation band assembly (230). The distal end of trocar actuationband assembly (230) is fixedly secured to the proximal end of trocarshaft (332). The proximal end of trocar actuation band assembly (230) isfixedly secured to the distal end of trocar actuation rod (220). Itshould therefore be understood that trocar (330) will translatelongitudinally relative to outer sheath (210) in response to translationof trocar actuation band assembly (230) and trocar actuation rod (220)relative to outer sheath (210). Trocar actuation band assembly (230) isconfigured to flex such that trocar actuation band assembly (230) mayfollow along the preformed curve in shaft assembly (200) as trocaractuation band assembly (230) is translated longitudinally relative toouter sheath (210). However, trocar actuation band assembly (230) hassufficient column strength and tensile strength to transfer distal andproximal forces from trocar actuation rod (220) to trocar shaft (332).Trocar actuation rod (220) is rigid. A clip (222) is fixedly secured totrocar actuation rod (220) and is configured to cooperate withcomplementary features within handle assembly (100) to prevent trocaractuation rod (220) from rotating within handle assembly (100) whilestill permitting trocar actuation rod (220) to translate longitudinallywithin handle assembly (100). Trocar actuation rod (220) furtherincludes a coarse helical threading (224) and a fine helical threading(226).

Shaft assembly (200) further includes a stapling head assembly driver(240) that is slidably received within outer sheath (210). The distalend of stapling head assembly driver (240) is fixedly secured to theproximal end of staple driver member (350). The proximal end of staplinghead assembly driver (240) is secured to a drive bracket (250) via a pin(242). It should therefore be understood that staple driver member (350)will translate longitudinally relative to outer sheath (210) in responseto translation of stapling head assembly driver (240) and drive bracket(250) relative to outer sheath (210). Stapling head assembly driver(240) is configured to flex such that stapling head assembly driver(240) may follow along the preformed curve in shaft assembly (200) asstapling head assembly driver (240) is translated longitudinallyrelative to outer sheath (210). However, stapling head assembly driver(240) has sufficient column strength to transfer distal forces fromdrive bracket (250) to staple driver member (350).

D. Exemplary Handle Assembly and User Input Features

As shown in FIG. 1, handle assembly (100) includes a casing (110) havinga lower portion that defines an obliquely oriented pistol grip (112) andan upper portion that supports a user interface feature (114) andreceives a battery pack (120), as described in greater detail below.Handle assembly (100) further includes several features that areoperable to actuate anvil (400) and stapling head assembly (300). Inparticular, handle assembly (100) includes a rotatable knob (130), asafety trigger (140) a firing trigger (150), a motor (160), and a motoractivation module (180). Knob (130) is coupled with trocar actuation rod(220) via a nut (not shown), such that coarse helical threading (224)will selectively engage a thread engagement feature within the interiorof the nut; and such that fine helical threading (226) will selectivelyengage a thread engagement feature within the interior of knob (130).These complementary structures are configured such that trocar actuationrod (220) will first translate proximally at a relatively slow rate,then translate proximally at a relatively fast rate, in response torotation of knob (130).

It should be understood that when anvil (400) is coupled with trocar(330), rotation of knob (130) will provide corresponding translation ofanvil (400) relative to stapling head assembly (300). It should also beunderstood that knob (130) may be rotated in a first angular direction(e.g., clockwise) to retract anvil (400) toward stapling head assembly(300); and in a second angular direction (e.g., counterclockwise) toadvance anvil (400) away from stapling head assembly (300). Knob (130)may thus be used to adjust a gap distance (d) between opposing surfaces(412, 322) of anvil (400) and stapling head assembly (300) until asuitable gap distance (d) has been achieved, for example as shown inFIG. 7C described below.

Firing trigger (150) is operable to activate motor (160) to therebyactuate stapling head assembly (300). Safety trigger (140) is operableto selectively block actuation of firing trigger (150) based on thelongitudinal position of anvil (400) in relation to stapling headassembly (300). Handle assembly (100) also includes components that areoperable to selectively lock out both triggers (140, 150) based on theposition of anvil (400) relative to stapling head assembly (300). Forinstance, safety trigger (140) may be blocked from rotating from anengaged position to a disengaged position until the position of anvil(400) relative to stapling head assembly (300) is within a predefinedrange. Accordingly, until the anvil position is within the predefinedrange, actuation of firing trigger (150) is blocked by safety trigger(140), thereby inhibiting firing of stapling head assembly (300).

Firing trigger (150) of the present example includes an integralactuation paddle (not shown), which may be similar to the paddledisclosed in U.S. Pub. No. 2017/0258471, incorporated by referenceabove. The paddle is configured to actuate a switch of motor activationmodule (180) (FIG. 1) when firing trigger (150) is pivoted to a firedposition. Motor activation module (180) is in communication with batterypack (120) and motor (160), such that motor activation module (180) isconfigured to provide activation of motor (160) with electrical powerfrom battery pack (120) in response to the paddle actuating the switchof motor activation module (180). Thus, motor (160) will be activatedwhen firing trigger (150) is pivoted. This activation of motor (160)will actuate stapling head assembly (300) via drive bracket (250), asdescribed in greater detail below. Though not shown, and by way ofexample only, motor (160) may be operatively coupled with drive bracket(250) via a gearbox coupled with an output shaft of motor (160), arotary cam member coupled with an output shaft of the gearbox, and a camfollower coupled with the rotary cam member, for example as disclosed inU.S. Pub. No. 2017/0258471, incorporated by reference above.

As best shown in FIGS. 1-2, handle assembly (100) is further configuredto releasably receive a battery pack (120) operable to provideelectrical power to motor (160), as noted above. It should be understoodthat battery pack (120) and handle assembly (100) may have complementaryelectrical contacts, pins and sockets, and/or other features thatprovide paths for electrical communication from battery pack (120) toelectrically powered components in handle assembly (100) when batterypack (120) is coupled with handle assembly (100). It should also beunderstood that, in some versions, battery pack (120) may be unitarilyintegrated within handle assembly (100) such that battery back (120)cannot be removed from handle assembly (100).

E. Exemplary Anastomosis Procedure with Circular Stapling Instrument

FIGS. 7A-7E show instrument (10) being used to form an anastomosis (70)between two tubular anatomical structures (20, 40). By way of exampleonly, the tubular anatomical structures (20, 40) may comprise sectionsof a patient's esophagus, sections of a patient's colon, other sectionsof the patient's digestive tract, or any other tubular anatomicalstructures. In some versions, one or more diseased portions of apatient's colon are removed, with the tubular anatomical structures (20,40) of FIGS. 7A-7E representing the remaining severed portions of thecolon.

As shown in FIG. 7A, anvil (400) is positioned in one tubular anatomicalstructure (20) and stapling head assembly (300) is positioned in anothertubular anatomical structure (40). In versions where tubular anatomicalstructures (20, 40) comprise sections of a patient's colon, staplinghead assembly (300) may be inserted via the patient's rectum. It shouldalso be understood that the procedure depicted in FIGS. 7A-7E is an opensurgical procedure, though the procedure may instead be performedlaparoscopically. Various suitable ways in which instrument (10) may beused to form an anastomosis (70) in a laparoscopic procedure will beapparent to those of ordinary skill in the art in view of the teachingsherein.

As shown in FIG. 7A, anvil (400) is positioned in tubular anatomicalstructure (20) such that shank (420) protrudes from the open severed end(22) of tubular anatomical structure (20). In the present example,purse-string suture (30) is provided about a mid-region of shank (420)to generally secure the position of anvil (400) in tubular anatomicalstructure (20). In some other variations, purse-string suture (30) istightened around the proximal end of shank (420). In some suchvariations, the proximal end of shank (420) may include a notch or otherfeature to securely capture purse-string suture (30). Continuing withthe present example, stapling head assembly (300) is positioned intubular anatomical structure (40) such that trocar (330) protrudes fromthe open severed end (42) of tubular anatomical structure (20). Apurse-string suture (50) is provided about a mid-region of shaft (332)to generally secure the position of stapling head assembly (300) intubular anatomical structure (40). Stapling head assembly (300) is thenurged distally to ensure that stapling head assembly (300) is fullyseated at the distal end of tubular anatomical structure (40).

Next, anvil (400) is secured to trocar (330) by inserting trocar (330)into bore (422) as shown in FIG. 7B. Latch members (430) engage head(334) of trocar (330), thereby providing a secure fit between anvil(400) and trocar (330). The operator then rotates knob (130) whileholding casing (110) stationary via pistol grip (112). This rotation ofknob (130) causes trocar (330) and anvil (400) to retract proximally. Asshown in FIG. 7C, this proximal retraction of trocar (330) and anvil(400) compresses the tissue of tubular anatomical structures (20, 40)between surfaces (412, 322) of anvil (400) and stapling head assembly(300). As this occurs, the operator may observe the tactile resistanceor feedback via knob (130) while turning knob (130), with such tactileresistance or feedback indicating that the tissue is being compressed.As the tissue is being compressed, the operator may visually observe theposition of an indicator needle (522) within a user interface feature(114) of handle assembly (100) to determine whether the gap distance (d)between opposing surfaces (412, 322) of anvil (400) and stapling headassembly (300) is appropriate; and make any necessary adjustments viaknob (130).

Once the operator has appropriately set the gap distance (d) via knob(130), the operator pivots safety trigger (140) toward pistol grip (112)to enable actuation of firing trigger (150). The operator then pivotsfiring trigger (150) toward pistol grip (112), thus causing paddle (158)to actuate the switch of motor activation module (180) and therebyactivate motor (160) to rotate. This rotation of motor (160) causesactuation (or “firing”) of stapling head assembly (300) by actuatingdrive bracket (250) distally to thereby drive knife member (340) andstaple driver member (350) distally, as shown in FIG. 7D. As knifemember (340) translates distally, cutting edge (342) of knife member(340) cuts excess tissue that is positioned within annular recess (418)of anvil (400) and the interior of knife member (340).

As shown in FIG. 3, anvil (400) of the present example includes abreakable washer (417) positioned within annular recess (418). Thiswasher (417) is broken by knife member (340) when the knife member (340)completes a full distal range of motion from the position shown in FIG.7C to the position shown in FIG. 7D. Features of stapler (10) may beconfigured to provide an increasing mechanical advantage as knife member(340) reaches the end of its distal movement, thereby providing greaterforce by which to break the washer (417). Of course, the breakablewasher (417) may be omitted entirely in some versions. In versions wherewasher (417) is included, it should be understood that washer (417) mayalso serve as a cutting board for knife member (340) to assist incutting of tissue.

As staple driver member (350) translates distally from the positionshown in FIG. 7C to the position shown in FIG. 7D, staple driver member(350) drives staples (90) through the tissue of tubular anatomicalstructures (20, 40) and into staple forming pockets (414) of anvil(400). Staple forming pockets (414) deform the driven staples (90) intoa “B” shape or a three-dimensional shape, for example, such that theformed staples (90) secure the ends of tissue together, thereby couplingtubular anatomical structure (20) with tubular anatomical structure(40).

After the operator has actuated stapling head assembly (300) as shown inFIG. 7D, the operator rotates knob (130) to drive anvil (400) distallyaway from stapling head assembly (300), increasing the gap distance (d)to facilitate release of the tissue between surfaces (412, 322). Theoperator then removes instrument (10) from the patient, with anvil (400)still secured to trocar (330). Referring back to the example where thetubular anatomical structures (20, 40) comprise sections of a patient'scolon, instrument (10) may be removed via the patient's rectum. Withinstrument (10) removed, the tubular anatomical structures (20, 40) areleft secured together by two annular arrays of staples (90) at ananastomosis (70) as shown in FIG. 7E. The inner diameter of theanastomosis (70) is defined by the severed edge (60) left by knifemember (340).

F. Exemplary User Interface Feature of Handle Assembly

As shown best in FIG. 8, handle assembly (100) of surgical staplinginstrument (10) further includes a user interface feature (114)configured to provide the operator with visual feedback indicating thepositioning of anvil (400) in relation to stapling head assembly (300)during a surgical procedure. The operator may thus observe userinterface feature (114) while rotating knob (130) to confirm whether asuitable gap distance (d) between anvil (400) and stapling assembly(300) has been achieved.

User interface feature (114) of the present example includes a graphicalindicator (500), which includes fixed linear indicia (502, 504, 506),graphical representations (510, 512) of staples, and a checkmark graphic(514). User interface feature (114) further defines a window (520)through which an indicator needle (522) may be viewed. In somevariations, user interface feature (114) further includes a field (530)that may indicate a diameter associated with the size of stapling headassembly (300), the size of staples in stapling head assembly (300), thesize of the gap defined between anvil (400) and stapling head assembly(300), and/or other information. By way of example only, field (530) mayindicate a stapling head assembly (300) size of 23 mm, 25 mm, 29 mm, or31 mm.

As the operator rotates knob (130) to adjust the longitudinal positionof anvil (400) relative to stapling head assembly (300), the operatormay observe the position of indicator needle (522) through window (520).Initially, indicator needle (522) may be positioned at or near thedistal end of window (520). As anvil (400) continues to move proximally,indicator needle (522) will eventually move proximally relative towindow (520). The operator may view the position of indicator needle(522) in relation to fixed linear indicia (502, 504, 506). Thedistal-most and proximal-most indicia (502, 506) may represent theboundaries of a “green zone,” which is the acceptable range of distancebetween anvil (400) and stapling head assembly (300) for successfulactuation of stapling head assembly (300). Thus, if indicator needle(522) is distal to distal-most indicia (502), the distance between anvil(400) and stapling head assembly (300) is too large; and if indicatorneedle (522) is proximal to proximal-most indicia (506), the distancebetween anvil (400) and stapling head assembly (300) is too small.Indicia (504) is longitudinally positioned between indicia (502, 506).Graphical representation (510) represents a relatively tall formedstaple (e.g., suitable for use in relatively thick tissue); whilegraphical representation (512) represents a relatively short formedstaple (e.g., suitable for use in relatively thin tissue). Graphicalrepresentations (510, 512) may thus facilitate the operator's decision,based on tissue observations or otherwise, on whether and how to achievea desired formed staple height by selecting an appropriate correspondingspatial relationship between indicator needle (522) and indicia (502,504, 506).

In the present example, window (520) is illuminated via a light emittingdiode (LED) (not shown), further facilitating viewing of indicatorneedle (522) in window (520). In addition, checkmark graphic (514) isilluminated via another LED (not shown) when stapling head assembly(300) completes a stapling and cutting cycle. Thus, the operator mayfurther rely on illumination of checkmark graphic (514) to confirm thatthe stapling and cutting cycle is complete, to thereby verify that it issafe to advance anvil (400) distally away from the anastomosis (70) torelease the tissue and thereafter remove instrument (10) from thepatient.

Circular surgical stapling instrument (10) may be further configured andoperable in accordance with at least some of the teachings of U.S. Pub.No. 2017/0258471, incorporated by reference above.

II. Exemplary Circular Surgical Stapling Instrument Having IndependentlyControlled Closure, Stapling, and Cutting

In some instances, it may be desirable to provide a version of circularsurgical stapling instrument (10) that exhibits powered actuation ofanvil (400) in addition to powered actuation of internal firingcomponents of stapling head assembly (300). Furthermore, it may bedesirable to provide such a version of instrument (10) with a pluralityof actuators that enable independent, powered actuation of anvil (400),staple driver member (350), and knife member (340), such that theresulting closure, stapling, and cutting strokes performed by such aninstrument may be controlled independently from one another in responseto user input.

While the teachings below are disclosed in the context of circularsurgical staplers, it will be appreciated that such teachings may beapplied to other types of surgical staplers as well. By way of exampleonly, such other staplers may include right-angle surgical staplers ofthe type disclosed in U.S. Pat. No. 10,045,780, entitled “Method ofApplying Staples in Lower Anterior Bowel Resection,” issued Aug. 14,2018, the disclosure of which is incorporated by reference herein.

A. Overview of Circular Surgical Stapling Instrument HavingIndependently Controlled Actuators

FIG. 9 shows an exemplary circular surgical stapling instrument (600)that exhibits a configuration and functionality of the kind describedabove. It will be understood that instrument (600) is similar toinstrument (10) described above except as otherwise described below.Similar to instrument (10), instrument (600) generally includes a bodyassembly in the form of a handle assembly (610), a shaft assembly (630)extending distally from handle assembly (610), a stapling head assembly(640) disposed at a distal end of shaft assembly (630), and an anvil(650) configured to releasably couple with an actuatable closure memberin the form of trocar (642) of stapling head assembly (640). Anvil (650)is selectively retractable and extendable by trocar (642) relative tostapling head assembly (640) for clamping tissue against a distallyfacing deck surface (644) thereof. Stapling head assembly (640) isselectively operable to eject staples distally into the clamped tissueand against anvil (650), and to cut the clamped tissue with acylindraceous knife member (not shown) similar to knife member (340)described above. Accordingly, stapling head assembly (640) and anvil(650) cooperate to define an end effector stapling assembly operable toclamp, staple, and cut tissue in response to user inputs.

Handle assembly (610) includes a casing (612) defining a pistol grip(614), a user interface (616) disposed on an upper side of casing (612)adjacent to a distal end of casing (612), and a knob (618) rotatablydisposed at a proximal end of casing (612). User interface (616) andknob (618) are similar to user interface (114) and knob (130) describedabove except as otherwise described below. Casing (612) of the presentexample includes an open-ended proximal cavity (not shown) configured toreleasably receive and retain a battery pack (620) similar to batterypack (120) and operable to power a motor unit (660) (see FIG. 10) housedwithin casing (612).

Handle assembly (610) of the present example further includes a safetymember (622), a closure trigger (624), and a firing trigger (626) eachmovable independently relative to pistol grip (614). Actuation ofclosure trigger (624) is configured to activate motor unit (660) toinitiate actuation of a trocar actuator (662) (see FIG. 10) and therebyeffect closure of anvil (650) relative to stapling head assembly (640)to clamp tissue therebetween. Actuation of firing trigger (626) isconfigured to activate motor unit (660) to initiate actuation of astaple actuator (664) and a knife actuator (666) (see FIG. 10) tothereby staple and cut the clamped tissue. As described in greaterdetail below in connection with FIG. 11, instrument (600) is configuredto control actuation of staple actuator (664) and knife actuator (666)independently in response to a single actuation of firing trigger (626).In this manner, a precise timing of the cutting stroke initiationrelative to the stapling stroke initiation may be achieved.

Safety member (622) of the present example is in the form of aprojection, such as a pivotable trigger similar to safety trigger (140),and is configured to directly or indirectly engage closure trigger (624)and/or firing trigger (626) to selectively block actuation thereof. Forinstance, safety member (622) may be configured to block actuation ofclosure trigger (624) until instrument (600) detects that anvil (650)has been fully attached to trocar (642). Additionally, or in thealternative, safety member (622) may be configured to block actuation offiring trigger (626) until anvil (650) has assumed a predeterminedlongitudinal position relative to stapling head assembly (640) thatdefines a particular gap distance (d) therebetween (see FIG. 7C).

Actuators (662, 664, 666) of instrument (600), shown schematically inFIG. 10, are configured to operatively couple corresponding actuatablecomponents of instrument (600) with motor unit (660). In particular,trocar actuator (662) operatively couples trocar (642) of stapling headassembly (640) with motor unit (660). Accordingly, trocar actuator (662)is configured to actuate trocar (642) and thus anvil (650) proximallyand distally in response to activation of motor unit (660) when motorunit (660) is operatively engaged with trocar actuator (662). Trocaractuator (662) may include an elongate member similar to trocaractuation rod (220) combined with trocar actuation band assembly (230)of instrument (10), which is translatably disposed within shaft assembly(630).

Staple actuator (664) operatively couples a staple driver member (notshown) of stapling head assembly (640) with motor unit (660)independently of trocar actuator (662). Accordingly, staple actuator(664) is configured to actuate the staple driver member, and thusstaples (not shown) housed within stapling head assembly (640), distallyin response to activation of motor unit (660) when motor unit (660) isoperatively engaged with staple actuator (664). Staple actuator (664)may include an elongate member similar to stapling head assembly driver(240) of instrument (10), which is translatably disposed within shaftassembly (630) independently of trocar actuator (662).

Knife actuator (666) operatively couples a cylindraceous knife member(not shown) of stapling head assembly (640) with motor unit (660)independently of trocar actuator (662) and staple actuator (664).Accordingly, knife actuator (666) is configured to actuate the knifemember longitudinally in response to activation of motor unit (660) whenmotor unit (660) is operatively engaged with knife actuator (666). Knifeactuator (666) may include an elongate member similar to stapling headassembly driver (240) of instrument (10), which is translatably disposedwithin shaft assembly (630) independently of trocar actuator (662) andstaple actuator (664). In this manner, actuators (662, 664, 666) areconfigured to cooperate with motor unit (660) to provide independentlyactuated clamping of tissue, stapling of the tissue, and cutting of thetissue.

Knob (618) of handle assembly (610) of the present example isoperatively coupled with trocar actuator (662) such that knob (618) isoperable as an anvil closure bailout feature. In that regard, trocaractuator (662) is driven primarily by motor unit (660) but is alsotranslatable longitudinally in response to rotation of knob (618), forexample when motor unit (660) is deactivated or otherwise disengagedfrom trocar actuator (662). Accordingly, knob (618) may be rotatedfollowing partial or full proximal retraction of anvil (650) towardstapling head assembly (640) to thereby extend anvil (650) distally awayfrom stapling head assembly (640), for example to release tissuecaptured therebetween. In such versions, knob (618) may be coupled withtrocar actuator (662) via features similar to those described above inconnection with knob (130) of instrument (10), including threadedportions (224, 226) of trocar actuation rod (220), for example. It willbe understood, however, that knob (618) may be omitted from instrument(600) in some versions such that trocar actuator (662) is driven solelyby motor unit (660).

Instrument (600) may be further configured and operable in accordancewith at least some of the teachings of U.S. Pat. No. 9,445,816, entitled“Circular Stapler with Selectable Motorized and Manual Control,” issuedSep. 20, 2016; U.S. Pat. No. 9,532,783, entitled “Circular Stapler withSelect Motorized and Manual Control, Including a Control Ring,” issuedJan. 3, 2017; U.S. Pat. No. 9,597,081, entitled “Motor Driven RotaryInput Circular Stapler with Modular End Effector,” issued Mar. 21, 2017;U.S. Pat. No. 9,463,022, entitled “Motor Driven Rotary Input CircularStapler with Lockable Flexible Shaft,” issued Oct. 11, 2016; U.S. Pub.No. 2018/0368836, entitled “Surgical Stapler with Independently ActuatedDrivers to Provide Varying Staple Heights,” published Dec. 27, 2018;and/or any of the other patent references identified herein, thedisclosures of which are incorporated by reference herein.

B. Exemplary Control System of Circular Surgical Stapling Instrument

As shown schematically in FIG. 10, instrument (600) further includes acontrol system (670) operable to control actuation of trocar actuator(662), staple actuator (664), and knife actuator (666) of instrument(600). Control system (670) includes a control module (672), motor unit(660), user interface (616), and a sensor (674) suitably arranged suchthat control module (672) communicates with each of motor unit (660),user interface (616), and sensor (674). Control module (672) includes aprocessor and is operable to store pre-programmed instrument controlalgorithms and receive input from user interface (616) and sensor (674).Based on these stored control algorithms and received input, controlmodule (672) is configured to control motor unit (660) with pulse-widthmodulation (PWM) to drive actuation of trocar actuator (662), stapleactuator (664), and knife actuator (666) independently from one anotherfor clamping, stapling, and cutting tissue.

Motor unit (660) includes one or more motors and is operatively coupledwith trocar actuator (662), staple actuator (664), and knife actuator(666). In some versions, motor unit (660) may comprise a single motoroperatively coupled with and configured to drive all three actuators(662, 664, 666). In such versions, motor unit (660) may be coupled withactuators (662, 664, 666) via one or more power transmission assemblies(not shown), such as a gear assembly, various suitable types of whichwill be apparent to those of ordinary skill in the art in view of theteachings herein and in the incorporated references. In other versions,motor unit (660) may comprise three motors, each being dedicated todrive a respective one of actuators (662, 664, 666). In furtherversions, motor unit (660) may comprise two motors, a first motor ofwhich is configured to drive trocar actuator (662) and a second motor ofwhich is configured to drive staple actuator (664) and knife actuator(666) with assistance of a power transmission assembly. It will beunderstood that motor unit (660) may comprise various other quantitiesand arrangements of motors in other versions.

Sensor (674) is arranged within or otherwise coupled to stapling headassembly (640), shaft assembly (630), or handle assembly (610), and isoperable to monitor one or more conditions of instrument (600) duringuse. For instance, sensor (674) may be configured to monitor translationof any one or more of actuators (662, 664, 666) and/or their adjoiningcomponents, such as trocar (642). In some such versions, sensor (674)may be mounted directly to any one of actuators (662, 664, 666) or anadjoining component thereof In other such versions, sensor (674) may befixedly mounted within stapling head assembly (640), shaft assembly(630), or handle assembly (610), such that actuators (662, 664, 666) andtheir adjoining components move relative to sensor (674).

In some versions, sensor (674) may be configured to detect secureattachment of anvil (650) to trocar (642), for example as disclosed inU.S. Pat. No. 10,307,157, incorporated by reference above; or in U.S.Pat. App. No. [Atty. Ref. END9142USNP1], entitled “Anvil Retention andRelease Features for Powered Circular Surgical Stapler,” filed on evendate herewith, the disclosure of which is incorporated by referenceherein. In other versions, sensor (674) may be configured to detectcertain characteristics of the particular stapling head assembly (640)coupled with shaft assembly (630), such as a diameter of stapling headassembly (640) or a size of the staples (not shown) housed therein. Insome such versions, sensor (674) may be configured to detect suchcharacteristics of stapling head assembly (640) via radio-frequencyidentification (RFID) of electronic information stored within a tagelement disposed on or within stapling head assembly (640), for exampleas disclosed in U.S. Provisional Pat. App. No. 62/868,457, entitled“Surgical Systems with Multiple RFID Tags,” filed on Jun. 28, 2019, thedisclosure of which is incorporated by reference herein.

Still in other versions, sensor (674) may be in direct communicationwith motor unit (660). For instance, sensor (674) may comprise a currentsensor operable to monitor an electrical current drawn by motor unit(660), or an encoder operable to monitor a rotational output of motorunit (660). Moreover, while only one sensor (674) is illustrated in thediagram of FIG. 10, it will be understood that sensor (674) may comprisea plurality of sensors, where each individual sensor (674) is configuredto monitor and communicate with control module (672) regarding arespective one or more conditions of instrument (600). Furthermore, itwill be understood that sensor (674) may be in the form of a sensorassembly that includes various suitable types of sensors readilyapparent to those of ordinary skill in the art in view of the teachingsherein and not otherwise described herein.

User interface (616) is similar to user interface (114) described above,except that user interface (616) is further configured to receive andcommunicate user input to control module (672). In that regard, userinterface (616) may include one or more buttons, dials, other actuatableelements, or displayed graphics that are selectable by a user toindicate certain information pertaining to a surgical procedure to beperformed or to stapling head assembly (640). By way of example only,such information may include any of the following: a desired stapleformation height; a corresponding gap between anvil (650) and stapling7head assembly (640) to which anvil (650) should be actuated duringclosure; a type or nominal thickness of tissue being fired upon withinstrument (600); and/or a diameter of stapling head assembly (640).Such information, in combination with information provided by sensor(674), may be used by control module (672) to adjust strokes and/orrates of actuation of actuators (662, 664, 666), and/or to adjust timingpauses between the powered actuations of actuators (662, 664, 666) toensure optimal clamping, stapling, and cutting of tissue during aprocedure, for example as described in greater detail below.

C. Exemplary Method for Controlling Circular Surgical Stapler

FIG. 11 shows an exemplary method (700) for controlling circularsurgical stapling instrument (600) via control system (670) shown inFIG. 10. At step (702), instrument (600) powers on in response to beingenergized by battery pack (620), for example when battery pack (620) isfully inserted into the proximal end of handle assembly (610) afterinstrument (600) is removed from product packaging. Upon removal fromthe packaging, anvil (650) is already secured to trocar (642) and is ina fully open state, and a staple retainer (646) (see FIG. 14) is securedto deck surface (644).

After instrument (600) powers on in the present example, control module(672) enters an anvil stroke calibration mode at step (704), which mayoccur automatically or in response to a user input, for example providedvia user interface (616). In this calibration mode, control module (672)activates motor unit (660) to drive trocar actuator (662) to retracttrocar (642) proximally and thereby close anvil (650) against the stapleretainer (646), or alternatively against deck surface (644) in the eventthat the staple retainer (646) has been removed. Control module (672)may detect that anvil (650) has reached a closed position by detectingvia sensor (674) an increase in the electrical current load of motorunit (660) upon contact of anvil (650) with the staple retainer (646) ordeck surface (644). Control module (672) observes the stroke (i.e.,longitudinal displacement) of anvil (650) during this retraction processand compares it to an expected stroke of anvil (650). Based on thiscomparison and any differences observed between the two stroke values,control module (672) then calibrates an actuation algorithm that isexecuted to activate motor unit (660) to actuate trocar actuator (662),and thereby ensure precise actuations of anvil (650) thereafter during asurgical procedure. In addition, or in the alternative, calibration ofthe anvil stroke may be performed by control module (672) in real timeduring a surgical procedure when anvil (650) is being retracted to clamptissue. Such calibration of the anvil stroke is described in furtherdetail below. It will be understood that the strokes of one or moreother actuatable members of instrument (600) may be calibrated in asimilar manner before or during a surgical procedure, and also that thecalibration of the anvil closure stroke may be applied by control module(672) to also calibrate the stapling stroke and/or the cutting stroke ofinstrument (600).

At step (706), control module (672) determines a diameter of staplinghead assembly (640). As described above, stapling head assembly (640)may be releasably attached to shaft assembly (630) such that staplinghead assemblies (640) of various diameters may be interchangeablycoupled with the distal end of shaft assembly (630) depending on a lumensize of the tissue structure being operated on with instrument (600).Control module (672) is configured to make this size determination basedon user input provided via user interface (616) and/or informationprovided by sensor (674), for instance when sensor (674) is configuredto detect the size of stapling head assembly (640) in the mannerdescribed above.

At step (708), control module (672) receives from user interface (616)input that indicates a desired height of staples to be formed in tissue,as selected by the operator via user interface (616). Control module(672) equates this staple height to a corresponding gap distance (d)(see FIG. 7C) to be established between anvil (650) and deck surface(644) of stapling head assembly (640) at a closed position of anvil(650), in order to achieve the selected staple height.

While steps (704, 706, 708) are shown in FIG. 11 as being performed in aparticular order, it will be appreciated that these steps (704, 706,708) may be performed in a variety of orders relative to one anotherfollowing the powering on of instrument (600) in step (702) and beforethe actuation of staple actuator (664) described below.

Following completion of steps (704, 706, 708), the operator detachesanvil (650) from trocar (642) and proceeds to position anvil (650)within a first tubular tissue structure of a patient and separatelyposition stapling head assembly (640) within a second tubular tissuestructure of the patient. The operator then attaches anvil (650) totrocar (642) within the patient, for example as shown in FIGS. 7A-7Bdescribed above, at which point control module (672) detects at step(710) that the attachment has been made. Such detection may be made bysensor (674), which communicates a corresponding signal to controlmodule (672).

At step (712), control module (672) detects that closure trigger (624)has been actuated by the operator. Control module (672) then proceeds tostep (714) and directs motor unit (660) to drive trocar actuator (662)to actuate trocar (642) proximally and thereby retract anvil (650) to aclosed position at which the selected staple height and correspondinggap distance (d) are achieved. In some versions, control module (672)may be configured to initiate retraction of trocar (642) and anvil (650)only in response to an actuation of closure trigger (624) that occursafter attachment of anvil (650) to trocar (642) has been detected atstep (710). The operator may monitor the retraction of anvil (650)toward its closed position via visual indicia and/or displayed graphicsof user interface (616).

Additionally, in some versions, control module (672) may control motorunit (660) to retract anvil (650) proximally through the anvil closurestroke in two sequential stages. For instance, control module (672) maydirect motor unit (660) to retract anvil (650) through a first portionof the anvil closure stroke, at which point control module (672) pausesactivation of motor unit (660) for a predetermined period of time (e.g.,several seconds). At the end of this wait period, control module (672)reactivates motor unit (660) to continue retracting anvil (650) throughthe remaining portion of the anvil closure stroke to its closedposition. Inclusion of such a pause in the retraction of anvil (650) mayenable the tissue being compressed between anvil (650) and deck surface(644) to at least partially settle (or “creep”). Advantageously, thissettling of tissue yields a reduction of the axial extension load ontrocar (642) and the resulting electrical current load of motor unit(660) as anvil (650) advances proximally to its fully closed positiondefined by the target staple height input provided by the user in step(708).

At step (716), control module (672) detects that firing trigger (626)has been actuated by the operator following completion of the anvilclosure stroke. In the present example, in response to detecting thisactuation, control module (672) observes completion of a predeterminedperiod of time measured from completion of the anvil closure stroke,during which staple actuator (664) and knife actuator (666) remainstationary. This wait period after anvil closure enables the clampedtissue to settle (or “creep”) into its fully compressed state beforestapling head assembly (640) is fired, thus reducing the axial loads onstaple actuator (664) and knife actuator (666), and the resultingcurrent loads of motor unit (660), during the respective stapling andcutting sequences. It will be understood that this wait period may beomitted in some versions.

Upon completion of the wait period denoted in step (718), control module(672) initiates distal actuation of the staple driver member (not shown)at step (720) to begin stapling the clamped tissue. In particular,control module (672) activates motor unit (660) to engage and drivestaple actuator (664) to actuate the staple driver member distallythrough stapling head assembly (640) and thereby drive staples intotissue and against anvil (650), for example similar to the manner shownin FIG. 7D. Upon initiating actuation of staple actuator (664), controlmodule (672) at step (722) observes another predetermined period of timeduring which motor unit (660) continues to drive staple actuator (664)through the stapling stroke. Simultaneously, at step (724) controlmodule (672) communicates with sensor (674) to detect when the stapledriver member reaches a predetermined longitudinal position withinstapling head assembly (640). Such a position may correspond to thepoint at which individual staple drivers (not shown), similar to stapledrivers (352) described above, reach deck surface (644) such that thestaples are at least partially formed within the clamped tissue. Thisprocess is described in further detail below in connection with FIGS.17-19.

In response to detecting completion of the predetermined time period ofstep (722) and/or detecting at step (724) that the staple driver memberhas reached the predetermined longitudinal position, control module(672) then initiates distal actuation of the knife member (not shown) atstep (726) to begin cutting the tissue. In particular, control module(672) activates motor unit (660) to engage and drive knife actuator(666) to actuate the knife member distally through stapling headassembly (640) and thereby cut the tissue, for example similar to themanner shown in FIG. 7D.

As noted above, delaying initiation of the cutting stroke relative toinitiation of the stapling stroke, as enabled by independent actuationof staple and knife actuators (662, 664, 666), ensures at least partialformation of staples within the tissue before tissue cutting commences.Advantageously, this approach enables the staples to anchor within theclamped tissue before cutting, and thereby prevent lateral shifting ofthe tissue and resulting malformation of the staples when the knifemember is driven distally.

The end of the distal cutting stroke of the knife member may correspondto a point at which the knife member breaks a washer (not shown) withinanvil (650) similar to washer (417) described above. Upon completion ofthe distal cutting stroke, control module (672) at step (728) directsmotor unit (660) to retract the knife member proximally back intostapling head assembly (640). In some versions, knife member distalextension and subsequent proximal retraction may be achieved by poweringmotor unit (660) through a continuous, uniform range of motion, forexample as disclosed in U.S. Pub. No. 2017/0258471 incorporated byreference above. In other versions, control module (672) may beprogrammed to communicate with sensor (674) to detect completion of thedistal cutting stroke, and thereafter specifically direct motor unit(660) to drive knife actuator (666) in an alternative manner to retractthe knife member proximally. In any of such versions, sensor (674) maycomprise an encoder configured to monitor a rotational output of motorunit (660).

Simultaneously with or subsequently to knife retraction step (728),control module (672) at step (730) directs motor unit (660) to drivetrocar actuator (662) distally to thereby extend anvil (650) distally toa predetermined position relative to deck surface (644) of stapling headassembly (640). This distal extension enables the stapled tissue to bereleased from between anvil (650) and stapling head assembly (640) sothat instrument (600) may be withdrawn from the patient while anvil(650) remains attached to trocar (642).

III. Exemplary Method for Calibrating Actuation Strokes of CircularSurgical Stapler

As described above, it may be desirable to calibrate the longitudinalactuations (or “strokes”) of trocar actuator (662), staple actuator(664), and knife actuator (666) before or during a surgical procedure.This ensures that the actual longitudinal displacements of anvil (650),the staple driver member (not shown), and the knife member (not shown)are consistent with corresponding expected longitudinal displacementsanticipated by control module (672) based on a given rotational outputof motor unit (660). As described below, proper calibration of thesestrokes enables circular stapler (600) to provide precise clamping,stapling, and cutting of patient tissue.

Control module (672) of the present example is configured to store andexecute a closure member actuation algorithm to longitudinally actuatetrocar actuator (662) (and thus trocar (642) and anvil (650)) to clamptissue; a staple driver member actuation algorithm to longitudinallyactuate staple actuator (664) (and thus staple driver member) to stapletissue; and a knife member actuation algorithm to longitudinally actuateknife actuator (666) (and thus knife member) to cut tissue. Each ofthese actuation algorithms stored by control module (672) comprises acorrelation between a given rotational output of motor unit (660) and anexpected longitudinal displacement of the corresponding actuated memberof stapler (600) effected by that particular rotational output. Asdescribed above, the rotational output of motor unit (660) may bemonitored by an encoder operatively coupled with motor unit (660) and incommunication with control module (672). As described below, thelongitudinal strokes of actuators (662, 664, 666) may be calibrated byadjusting the corresponding actuation algorithms stored by controlmodule (672).

A. Exemplary Actuation Stroke Calibration Method

FIG. 12 shows an exemplary method for calibrating the stroke of at leasttrocar actuator (662) (and the connected trocar (642) and anvil (650))by adjusting the closure member actuation algorithm to redefine thecorrelation between rotational output of motor unit (660) andlongitudinal displacement of trocar actuator (662). As described abovein connection with step (704) of operation method (700) shown in FIG.11, this calibration process may be performed upon an initialunpackaging of circular stapler (600) prior to a surgical procedure.Additionally, or in the alternative, this calibration process may beperformed in real-time during a surgical procedure, as described ingreater detail below. Furthermore, as described below, the adjustment ofthe closure member actuation algorithm can be used by control module(672) to also adjust the staple driver member actuation algorithm andthe knife member actuation algorithm, to thereby calibrate the stapledriver member stroke and the knife member stroke. In some versions,however, steps similar to those shown in FIG. 12 may be performed bycontrol module (672) to adjust the staple driver member actuationalgorithm and the knife member actuation algorithm independently of theclosure member actuation algorithm.

As shown in FIG. 12, calibration method (800) begins at step (802) withan initiating event, which may be an initial mating of battery pack(620) with handle assembly (610) after device unpackaging, oralternatively an actuation of closure trigger (624) following attachmentof anvil (650) to trocar (642) during a surgical procedure. In responseto the initiating event (802), control module (672) executes the storedclosure member actuation algorithm at step (804) to activate motor unit(660) to actuate trocar actuator (662) proximally to transition anvil(650) toward a closed state. Prior to or during execution of the closuremember actuation algorithm, control module (672) determines at step(806) that a monitored one of trocar actuator (662), trocar (642), oranvil (650) (each a “closure member” herein) is in a first predeterminedposition, for example via detection by sensor (674) in the form of aposition sensor. By way of example only, the first predeterminedposition may correspond to anvil (650) in a fully open state (X_(O)) asshown in FIG. 13A, in which anvil (650) is in a distal-most positionrelative to deck surface (644). In other examples, the firstpredetermined position may correspond to anvil (650) in a partiallyclosed state. Motor unit (660) continues to retract trocar actuator(662) proximally while control module (672) observes an actuallongitudinal displacement of one of the monitored closure member (642,650, 662) at step (808), for example via sensor (674) in the form of asensor. It will be understood that trocar actuator (662), trocar (642),and anvil (650) of the present example translate together such thattheir longitudinal displacements are the same for a given output ofmotor unit (660).

At step (810), control module (672) determines that the monitoredclosure member (642, 650, 662) has reached a second predeterminedposition located proximal to the first predetermined position. By way ofexample only, the second predetermined position may correspond to anvil(650) in an initially closed state in which anvil (650) confronts but isnot drawn against deck surface (644), for example as shown by position(X_(C)) in FIG. 13B. In other versions, the second predeterminedposition may correspond to anvil (650) in a fully closed and overloadedstate in which anvil (650) is compressed against deck surface (644) oranother structure. For instance, FIG. 13C shows anvil (650) in anexemplary fully closed and overloaded state (X_(OL)) in which anvil(650) is drawn against deck surface (644). FIG. 14 shows anotherexemplary fully closed and overloaded state (X_(OL)) of anvil (650) inwhich anvil (650) is drawn against a staple retainer (646) prior to theremoval of retainer (646) from stapling head assembly (640) afterunpackaging of circular stapler (600). In that regard, it will beunderstood that FIGS. 13A-14 illustrate exemplary positions of anvil(650) in the absence of tissue, for example prior to performance of asurgical procedure on a patient. As described above, however,calibration method (800) may also be performed in real-time during asurgical procedure while anvil (650) is being closed on patient tissue.

In any such versions where the second predetermined position of themonitored closure member (642, 650, 662) corresponds to a state in whichanvil (650) is drawn against another structure (e.g., deck surface(644), staple retainer (646), or patient tissue), reaching of the secondpredetermined position may be identified by control module (672) basedon an observed increase in load on the closure system components. Thisload may be detected in the form of a longitudinal force exerted ontrocar actuator (662) (and thus also anvil (650) and trocar (642)), oran electrical current drawn by motor unit (660) while actuating trocaractuator (662). In that regard, it will be understood that closure ofanvil (650) against a structure induces a longitudinal extension forcein anvil (650), trocar (642), and trocar actuator (662) that makesfurther proximal retraction of these closure components by motor unit(660) more difficult, thus increasing the electrical current load ofmotor unit (660). This increase in closure load may be detected by oneor more sensors in the form of a current sensor or a force sensor thatcommunicate with control module (672).

Upon determining that the monitored closure member (642, 650, 662) hasreached the second predetermined position, control module (672) proceedsto step (812) and compares the actual longitudinal displacement of themonitored closure member (642, 650, 662) observed by control module(672), via one or more sensors (674), to an expected longitudinaldisplacement stored by control module (672). Control module (672)evaluates at step (814) whether there is a difference between theobserved actual longitudinal displacement and the stored expectedlongitudinal displacement. If the two longitudinal displacement valuesare equal or within a predetermined acceptable range of one another suchthat there is no significant difference, control module (672) proceedsto step (816) to execute the original stored actual algorithms inresponse to user actuations of closure trigger (624) and firing trigger(626), for example as outlined above in the steps of method (700).

Alternatively, if control module (672) determines that there is asignificant difference between the actual and expected longitudinaldisplacements, control module (672) proceeds to step (818) to adjust atleast the closure member actuation algorithm based on the determineddifference. More specifically, in the present example, control module(672) redefines the stored correlation between a given rotational outputof motor unit (660) and the corresponding expected longitudinaldisplacement of the monitored closure member (642, 650, 662). The newlydefined correlation relates the observed actual longitudinaldisplacement of the closure member (642, 650, 662) with the rotationaloutput of motor unit (660) during the observed longitudinal displacementof the closure member (642, 650, 662). This rotational output of the newcorrelation may be the same as or different than the rotational outputof the original correlation.

In some versions, the staple member actuation algorithm and the knifemember actuation algorithm may be adjusted in a similar manner based onthe same difference value determined by control module (672) inconnection with actuation of the monitored closure member (642, 650,662). It will be understood that calibration of all three actuationalgorithms ensures precise longitudinal actuation of anvil (650), thestaple driver member, and the knife member of stapler (600). Afteradjusting the closure member actuation algorithm, and optionally alsothe staple driver member and knife member actuation algorithms, controlmodule (672) proceeds to step (820) to execute the adjusted actualalgorithms in response to user actuations of closure trigger (624) andfiring trigger (626), for example as outlined above in the steps ofmethod (700).

As noted above, it will be appreciated that the closure membercalibration process (800) of FIG. 12 may be performed prior to asurgical procedure such that the longitudinal stroke of trocar actuator(662) (and trocar (642) and anvil (650)) is properly calibrated beforeclamping tissue. Additionally, or in the alternative, calibrationprocess (800) may be performed one or more times during a surgicalprocedure on tissue to ensure that the longitudinal stroke of trocaractuator (662), and optionally also the longitudinal strokes of stapleactuator (664) and knife actuator (666), remain properly calibratedthroughout use.

FIG. 15 depicts a line graph (830) showing an exemplary calibration ofthe longitudinal stroke of trocar actuator (662) (and thus trocar (642)and anvil (650)) per method (800) described above. The X-axis of graph(830) represents time and the Y-axis of graph (830) represents a distaldisplacement (δ) of trocar actuator (662) relative to a proximal-mostposition (i.e., a distal displacement of anvil (650) relative to decksurface (644)), as interpreted by control module (672). A firsthorizontal portion (834) of the illustrated curve (832) indicates trocaractuator (662) in a dully extended position at displacement (61) beforecalibration of the longitudinal stroke. In the present example, trocaractuator (662) remains in the fully extended position throughout initialevents including removal of stapler (600) from package as indicated byvertical dashed line (836), attachment of battery pack (620) to handleassembly (610) as indicated by vertical dashed line (838), andattachment of anvil (650) to trocar (642) as indicated by verticaldashed line (840).

First descending portion (842) of curve (832) represents initialproximal retraction of trocar actuator (662) to transition anvil (650)from the fully open position to a partially closed position at a first,rapid actuation rate. Second descending portion (844) of curve (832)represents final proximal retraction of trocar actuator (662) totransition anvil (650) from the partially closed state to a fully closedstate at a second, slower actuation rate. Upon anvil (650) reaching thefully closed and overloaded state (X_(OL)), motor unit (660) experiencesa sudden increase in electrical current load, as represented by verticalline (846). Control module (672) detects this increase in electricalcurrent load via sensor (674) and thereby determines that anvil (650)has reached the fully closed state. Control module (672) then proceedsto compare the actual observed longitudinal displacement of trocaractuator (662) observed during proximal retraction with an expectedlongitudinal displacement, and control module (672) determines adifference between the two values.

In the present example, control module (672) adjusts the closure memberactuation algorithm based on the determined difference to therebyre-“zero” the proximal end of longitudinal stroke of trocar actuator(662), for example via the steps described above in connection withmethod (800). Subsequently, control module (672) executes the adjustedclosure member actuation algorithm to extend trocar actuator (662)distally to a fully extended state and thereby return anvil (650) to afully open state (X_(O)), as represented by ascending curve portion(848). Because the longitudinal stroke is now calibrated with a proper“zero” point, the fully extended state of trocar actuator (662) andcorresponding fully open state (X_(O)) of anvil (650) registers as anew, greater displacement (62) on the displacement scale applied bycontrol module (672). As shown on graph (830), the difference betweenthe original displacement value (61) and the adjusted displacement value(62) correlated by control module (672) with a fully extended state oftrocar actuator (662) (i.e., the fully open state (X_(O)) of anvil(650)) is equal to the displacement amount by which the “zero” point oftrocar actuator (662) is adjusted by control module (672).

Execution of the adjusted closure member actuation algorithm forsubsequent actuations of trocar actuator (662) ensures accuratepositioning of anvil (650) relative to deck surface (644), and thusprecise clamping of tissue per user inputs. As described above, controlmodule (672) may apply this calibration of the closure member actuationalgorithm to also calibrate the staple member actuation algorithm andthe knife member actuation algorithm, thus providing precise staplingand cutting of tissue as well.

B. Exemplary Actuation of Stapling Head Assembly per User-SpecifiedTissue Gap

As described above, user interface (616) of circular surgical stapler(600) is configured to receive and communicate user input to controlmodule (672). As shown in FIG. 16, a visual display (680) of userinterface (616) (which may be in the form of a window similar to window(520) in other versions) includes a distal linear indicia (682) and aproximal linear indicia (684). Linear indicia (682, 684) define theboundaries of an acceptable range (referred to as a “green zone”) of atissue gap defined longitudinally between anvil (650) and deck surface(644) of stapling head assembly (640) to enable proper formation ofstaples fired into tissue. Distal linear indicia (682) indicates a largetissue gap setting that provides anvil (650) in a distal, “tall” closedposition (A_(T)) to define a large tissue gap (δ_(AT)) between anvil(650) and deck surface (644), as shown in FIG. 17A. Proximal linearindicia (684) indicates a small tissue gap setting that provides anvil(650) in a proximal, “low” closed position (A_(L)) to define a smalltissue gap (δ_(AT)) between anvil (650) and deck surface (644), as shownin FIG. 17B. As indicated by symbols (686, 688) of user interface (616),the large tissue gap setting results in formation of staples (692) witha taller formed height (e.g., for thicker tissues), and the small tissuegap setting results in formation of staples (692) with a shorter formedheight (e.g., for thinner tissues).

User interface (616) includes one or more selectable input features thatenable a user to specify a desired tissue tap setting for anvil (650) inthe closed position, which is then communicated by user interface (616)to control module (672). As described above in connection with step(714) of method (700), control module (672) is configured to controlmotor unit (660) to retract trocar actuator (662) proximally until anvil(650) achieves the target tissue gap setting specified via the userinput. This may be confirmed by control module (672) via communicationwith sensor (674) in the form of a position sensor, which may be locatedin stapling head assembly, for example. As described above in connectionwith FIGS. 12-15, the longitudinal stroke of trocar actuator (662) maybe calibrated before and/or during closure of anvil (650) on patienttissue such that the actual tissue gap (δ) defined between anvil (650)and deck surface (644) is equal to the target tissue gap (δ) specifiedby the user via user interface (616).

The target tissue gap (δ) input by user via user interface (616) may bereferenced by control module (672) in controlling other operationalaspects of stapler (600) as well. For instance, in addition tocontrolling the longitudinal displacement of trocar actuator (662)during the anvil closure stroke, control module (672) may also controlthe longitudinal displacement of staple actuator (664) during thestapling stroke and the longitudinal displacement of knife actuator(666) during the cutting stroke based on the tissue gap user input. Inparticular, control module (672) may tailor the longitudinaldisplacements of each actuator (662, 664, 666) to ensure that actuators(662, 664, 666) are actuated longitudinally by the appropriate amount toprovide a full stapling stroke and a full cutting stroke withoutunder-actuation or over-actuation relative to the target tissue gap. Inthat regard, it will be appreciated that calibration of the longitudinalstrokes of staple actuator (664) and knife actuator (666) may bedesirable to ensure that staple actuator (664) and knife actuator (666)are actuated by the appropriate amount during a surgical procedure. Asdescribed above, the corresponding staple member actuation algorithm andknife member actuation algorithm may be adjusted appropriately based onthe adjustments made to the closure member actuation algorithm viacalibration method (800). Alternatively, the staple member actuationalgorithm and knife member actuation algorithm may be adjustedindependently of the closure member actuation algorithm, for example viasteps similar to those of method (800).

The target tissue gap user input may also be reference by control module(672) to control a rate of actuation of one or more of actuators (662,664, 666). For instance, control module (672) may decrease the actuationrates of one or more actuators (662, 664, 666) for larger tissue gapsand increase the actuation rates of one or more actuators (662, 664,666) for smaller tissue gaps. In that regard, it will be appreciatedthat larger tissues gaps are often selected to accommodate thickertissues, which can induce higher electrical current loads for motor unit(660) during stapling and cutting. Reducing the actuation rate of stapleactuator (664) and knife actuator (666) for thicker tissues can thushelp to maintain the electrical current load of motor unit (660) below adesired threshold.

IV. Exemplary Method of Controlling Knife Member Actuation Relative toStaple Driver Member Actuation

As described above in connection with steps (720-726) of method (700),control module (672) is configured to control motor unit (660) toactuate staple actuator (664) and knife actuator (666) independentlysuch that the knife member is actuated distally only once the staples(692) driven by the staple driver member are at least partially formedwithin the tissue by anvil (650). More specifically, control module(672) communicates with sensor (674) to detect when staple actuator(664), the staple driver member (not shown), or individual stapledrivers (690) (see FIG. 18) of the staple driver member reaches apredetermined longitudinal position in which the upper end of stapledrivers (690) and crowns (694) of staples (692) are positioned at decksurface (644) such that staple legs (696) are partially deformed byanvil (650), for example as shown and described below in connection withFIG. 19B.

FIGS. 18 and 19A show an exemplary staple driver (690) of the stapledriver member of circular stapler (600) in a fully recessed position(D₀) within a respective staple opening (699) of stapling head assembly(640). Though not shown, it will be appreciated that the staple drivermember (not shown) of stapling head assembly (640) includes a pluralityof staple drivers (690) arranged annularly similar to staple drivers(352) of staple driver member (350) described above. Each staple driver(690) is slidably arranged within a respective staple opening (699) of adeck member (698) and has an upper end that supports the crown (694) ofa respective staple (692). As staple actuator (664) is driven distallyby motor unit (660) in response to activation by control module (672),staple driver (690) drives the respective staple (692) distally fromstaple opening (699), as shown in FIGS. 19B and 19C. FIG. 19B showsstaple driver (690) in a partially extended position (D₁) in which theupper end of staple driver (690) and the staple crown (694) arepositioned at an upper end of staple opening (699), in line with decksurface (644). In this position, staple legs (696) have been received bystaple forming pockets (652) of anvil (650) such that staple legs (696)are partially deformed within the tissue (not shown) clamped betweenanvil (650) and deck surface (644). FIG. 19C shows staple driver (690)in a fully extended position (D2) in which staple legs (696) of staple(692) are fully formed against anvil (650), within the clamped tissue.As shown in FIGS. 19B and 19C, the free ends of staple legs (696) in aformed state are bent proximally toward staple crown (694).

Control module (672) of the present version is configured to initiatedistal actuation of knife actuator (666) (and thus the knife member)upon determining that staple drivers (690) have reached the partiallyextended position (D₂) shown in FIG. 19B. This determination by controlmodule (672) may be made via communication with one or more sensorsconfigured to monitor the longitudinal position of one or more of stapleactuator (664), the staple driver member, or staple drivers (690).Additionally, as noted above, calibrating the longitudinal stroke oftrocar actuator (662) prior to actuating staple actuator (664) ensuresthat anvil (650) in the closed position defines the proper tissue gap(δ) relative to deck surface (644), consistent with the target tissuegap specified via user interface (616). This in turn ensures that distalactuation of knife actuator (666) does not begin until staple legs (696)are indeed at least partially deformed by the amount expected based onthe user-specified target tissue gap. This approach ensures that theclamped tissue is not disrupted via engagement by the knife memberduring the initial stage of staple formation. Advantageously, thisenables staples (692) to form properly within the clamped tissue,thereby maximizing hemostasis along the formed staple line.

FIG. 20 depicts a line graph (900) showing exemplary curves thatrepresent actuation over time of the trocar actuator (662), stapleactuator (664), and knife actuator (666) by motor unit (660) duringexemplary surgical procedures on thin tissue, medium thickness tissue,and thick tissue. An anvil displacement curve (902) representslongitudinal displacement over time of trocar actuator (662), and thustrocar (642) and anvil (650). As dashed lower portion (904) of anvildisplacement curve (902) represents an original intended closure strokeof anvil (650) prior to calibration of the closure member actuationalgorithm in the manner described above.

A first motor load curve (910) represents electrical current load ofmotor unit (660) while actuating staple actuator (664) and thus thestaple driver member and its staple drivers (690) to drive staples (692)distally against anvil (650), through thin tissue. A second motor loadcurve (912) represents electrical current load of motor unit (660) whileactuating staple actuator (664) and thus the staple driver member andits staple drivers (690) to drive staples (692) distally against anvil(650), through medium thickness tissue. A third motor load curve (914)represents electrical current load of motor unit (660) while actuatingstaple actuator (664) and thus the staple driver member and its stapledrivers (690) to drive staples (692) distally against anvil (650),through thick tissue. A first knife displacement curve (920) representslongitudinal displacement over time of knife actuator (666), and thusthe knife member, through thin tissue. A second knife displacement curve(922) represents longitudinal displacement over time of knife actuator(666), and thus the knife member, through medium thickness tissue. Athird knife displacement curve (924) represents longitudinaldisplacement over time of knife actuator (666), and thus the knifemember, through thick tissue.

As shown by motor load curves (910, 912, 914) and knife displacementcurves (920, 922, 924), control module (672) of the present example isconfigured to control motor unit (660) to actuate staple actuator (664)and knife actuator (666) distally more slowly as tissue thicknessincreases. This is evident in graph (900) by the horizontally elongatedconfiguration of medium tissue thickness curves (912, 922) and thicktissue curves (914, 924) relative to thin tissue curves (910, 920). Thisapproach ensures that the electrical current load of motor unit (660)does not exceed a predetermined threshold value during the stapling andcutting strokes. In that regard, as described above, distal actuation ofstaples (692) and the knife member through tissue of increasingthicknesses causes motor unit (660) to draw higher current loads.

Each motor load curve (910, 912, 914) includes a first rise (A) thatreflects distal actuation of staple actuator (664) through a firstportion of the stapling stroke that actuates staple drivers (690) fromthe full recessed position (D₀) to the emerging position (Di), shown inFIGS. 18-19B, thus driving staples (692) through an initial stage offormation against anvil (650). Each motor load curve (910, 912, 914)further includes a second rise (B) that reflects distal actuation ofstaple actuator (664) through a second portion of the stapling strokethat actuates staple drivers (690) from the emerging position (D₁) tothe fully extended position (D₂), shown in FIGS. 19B-19C, thus drivingstaples (692) distally through a final stage of formation against anvil(650). As shown by graph (900) for each of the three tissue thicknessscenarios, control module (672) initiates distal actuation of knifeactuator (666) to perform the cutting stroke when staple drivers (690)have reached their emerging positions (D₁), represented by motor loadcurves as the transition between first and second curve portions (A, B).As described above in connection with FIGS. 18-19C, this approach ofstaggering the initiation of the stapling and cutting strokes serves tomitigate risk of staple malformation, thus ensuring properly formedstaples in patient tissue. In the present example, graph (900) shows anexemplary time difference (Δt) between initiation of knife actuator(666) in a procedure on thin tissue and initiation of knife actuator(666) in a procedure on thick tissue.

In versions of circular stapler (600) in which sensor (674) includes acurrent sensor operatively coupled with motor unit (660) in the mannerdescribed above, control module (672) may control an actuation rate (or“velocity”) of one or more actuators (662, 664, 666) and theircorresponding components based on the electrical current drawn by motorunit (660) as detected by the current sensor. For instance, in responseto an increase in detected current load above a predetermined threshold,control module (672) may decrease the actuation rate of the actuator(662, 664, 666) being actuated. Similarly, in versions of stapler (600)where sensor (674) includes a force sensor operatively coupled with oneor more of trocar actuator (662), staple actuator (664), knife actuator(666), or their related components (e.g., trocar (642)), control module(672) may be configured to decrease an actuation rate of a particularactuator (662, 664, 666) in response to detecting an increase inlongitudinal force exerted on that actuator (662, 664, 666) duringactuation thereof.

It will be appreciated that the actuation rates of one or more actuators(662, 664, 666) may be controlled based on additional factors as well,such as a size of stapling head assembly (640) or a target tissue gapspecified by a user via user interface (616). By way of example only,control module (672) may decrease the actuation rates of one or moreactuators (662, 664, 666) in the presence of a stapling head assembly(640) of a relatively larger diameter; and increase the actuation ratesof one or more actuators (662, 664, 666) in the presence of a staplinghead assembly (640) of a relatively smaller diameter. Additionally,control module (672) may decrease the actuation rates of one or moreactuators (662, 664, 666) for larger tissue gaps and increase theactuation rates of one or more actuators (662, 664, 666) for smallertissue gaps.

V. Exemplary Identification of Stapling Head Assembly via RadioFrequency Identification

As described above, it may be desirable in some instances to detectcertain characteristics of stapling head assembly (640) (e.g., diameter)via sensor (674) and communicate such information to control module(672), particularly in instances in which stapling head assemblies (640)of various different types are interchangeable with shaft assembly(630). As shown in FIG. 9, end effector (640, 650) of surgicalinstrument (600) may include a radio frequency identification (RFID) tag(1000) configured to store information pertaining to selectedcharacteristics of end effector (640, 650). Additionally, one of shaftassembly (630) or handle assembly (610) may include a sensor (674) inthe form of an RFID scanner configured to read the information stored byRFID tag (1000) and communicate such information to control module(672). Based on such information, control module (672) may suitablyadjust one or more actuation algorithms of actuators (662, 664, 666) toensure appropriate longitudinal displacements, actuation rates, and/ortime pauses between strokes of actuators (662, 664, 666), for example asdescribed in greater detail below and in U.S. Provisional Pat. App. No.U.S. Provisional Pat. App. No. 62/868,457, incorporated by referenceabove.

As shown in FIG. 21, a graph (2260) represents a relationship betweenfiring Load (lbs) on the Y-axis and firing time (sec) on the X-axis.Graph 21 depicts a default, unadjusted, firing algorithm (2263) and anadjusted firing algorithm (2263). The graph 2260 further depicts adefault maximum firing load threshold (2261) (e.g. 400 lbs) and a finalmaximum firing load threshold (2262) (e.g. 485 lbs) for a firing loadapplied by motor unit (660) to stapling head assembly (640), via stapleactuator (664) and knife actuator (666). The default maximum firing loadthreshold (2261) is adjusted to the final maximum firing load threshold(2262) based on end-effector information of the end effector (640, 650)that is stored in RFID tag (1000) of stapling head assembly (640) andread by RFID scanner (674). In the example of FIG. 21, the end-effectorinformation represents a stapling head assembly (640) (or “staplecartridge”) that comprises a larger size (e.g. 31 mm) than a defaultstaple cartridge (e.g. 25 mm). The default staple cartridge size (e.g.25 mm) is associated with the default firing algorithm (2263) anddefault maximum firing load threshold (2261). Meanwhile, the largerstaple cartridge size (e.g. 31 mm) is associated with the final firingalgorithm (2264) and final maximum firing load threshold (2262).

The end-effector information stored in the RFID tag (1000) can includethe staple cartridge size and/or a firing load adjustment value (e.g. 85lbs) based on the cartridge size. In the event of the staple cartridgesize, the control module (672) can use a database or a lookup table ofstaple cartridge sizes and corresponding firing load adjustment valuesto look up a suitable firing load adjustment values.

Further, input from the RFID scanner (674) indicative of theend-effector information causes the control module (672) to adjust thedefault maximum firing load threshold (2261) (e.g. 400) to the finalmaximum firing load threshold (2262) (e.g. 485 lbs), and maintain afiring algorithm (2264) below the final maximum firing load threshold(2262), as illustrated in FIG. 21.

In the example of FIG. 21, the control module (672) adjusts orintroduces a minimum wait-time “t” before causing the motor unit (660)to apply the firing algorithm (2263) to the end effector (640, 650). Invarious instances, the minimum wait-time “t” is a time period betweencompletion of a closure sequence of an end effector of the surgicalinstrument (600), where tissue is grasped by the end effector (640, 650)in a closed configuration, and commencement of a firing sequence of theend effector (640, 650), where the grasped tissue is stapled and cut.The minimum wait time “t” permits tissue creep where the grasped tissueadjusts to a lower average pressure thereby reducing the maximum firingload necessary to complete the firing sequence of the end effector (640,650) to a value at or below the final maximum firing load threshold(2262). In the default firing algorithm (2263), without the minimumwait-time “t”, the firing algorithm (2263) must be interrupted (2267)for a time period from time t3 to time t4 to prevent the firing loadfrom exceeding the final maximum firing load threshold (2262). Bycomparison, the firing algorithm (2264) is continued through the timeperiod between t3 and t4, as illustrated in FIG. 21.

Referring still to FIG. 21, another factor that can influence theminimum wait time “t” is the user-selected form height of the staples(692) deployed from the stapling head assembly (640), which is directlyproportional to tissue gap distance defined by anvil (650) in the closedposition, as described above. As also described above, control module(672) may be configured to prompt a user through user interface (616) toselect a desired staple form height (i.e., tissue gap). In at least oneexample, the control module (672) can present the user with a pluralityof staple form heights from which to select. Additionally, oralternatively, the control module (672) can recommend an optimal formheight based on the tissue being treated by the surgical instrument(600). In any event, the user-selected form height can cause the controlmodule (672) to further adjust the minimum wait time “t”. In at leastone example, the control module (672) stores, in a database or a lookuptable, form heights and corresponding wait-time adjustments. The controlmodule (672) can adjust the minimum wait time “t” by identifying await-time adjustment associated with a user-selected form height, andthen adjusting the minimum wait time “t” in accordance with theidentified wait-time adjustment.

Generally, a more formed staple is associated with a greater firingload, and requires a greater minimum wait time “t” than a lesser formedstaple. In the example of FIG. 21, the user-selected form height (2265)is associated with a firing load “F2”, and is greater than a minimumform height (2266) associated with a minimum firing load “F1”. Theminimum firing loads “F1” and “F2” represent firing loads at whichstaple legs begin to buckle. Accordingly, in the example illustrated inFIG. 21, the selected wait time “t” is a result of the selected largersize staple cartridge and the selected form height (2265).

VI. Exemplary Combinations

The following examples relate to various non-exhaustive ways in whichthe teachings herein may be combined or applied. The following examplesare not intended to restrict the coverage of any claims that may bepresented at any time in this application or in subsequent filings ofthis application. No disclaimer is intended. The following examples arebeing provided for nothing more than merely illustrative purposes. It iscontemplated that the various teachings herein may be arranged andapplied in numerous other ways. It is also contemplated that somevariations may omit certain features referred to in the below examples.Therefore, none of the aspects or features referred to below should bedeemed critical unless otherwise explicitly indicated as such at a laterdate by the inventors or by a successor in interest to the inventors. Ifany claims are presented in this application or in subsequent filingsrelated to this application that include additional features beyondthose referred to below, those additional features shall not be presumedto have been added for any reason relating to patentability.

EXAMPLE 1

A method of operating a powered surgical stapler having a motor unit, acontroller in communication with the motor unit, and a stapling assemblyoperatively coupled with the motor unit and having a closure member, astaple driver member, and a knife member, wherein the stapling assemblyis actuatable between an open state for receiving tissue and a closedstate for clamping tissue, the method comprising: (a) receiving with thecontroller a user input that indicates a tissue gap to be defined by thestapling assembly in the closed state; (b) based on the user input,controlling the motor unit to actuate the closure member to transitionthe stapling assembly to the closed state to define the tissue gap andclamp tissue therein; (c) with the stapling assembly in the closedstate, controlling the motor unit to actuate the staple driver member todrive staples into the clamped tissue; (d) after initiating actuation ofthe staple driver member, determining with the controller that thestaple driver member has reached a predetermined longitudinal position;and (e) in response to the determination, controlling the motor unit toinitiate actuation of the knife member to cut the clamped tissue.

EXAMPLE 2

The method of Example 1, wherein the closure member, the staple drivermember, and the knife member are actuatable by the motor unitindependently of one another.

EXAMPLE 3

The method of any of the preceding Examples, wherein actuating thestaple driver member to drive staples into the clamped tissue andactuating the knife member to cut the clamped tissue comprise actuatingthe staple driver member and the knife member distally relative to themotor unit.

EXAMPLE 4

The method of any of the preceding Examples, wherein the staplingassembly includes an anvil, wherein each staple includes a crown and apair of legs, wherein the predetermined longitudinal position of thestaple driver member comprises a position in which the legs have been atleast partially deformed by the anvil.

EXAMPLE 5

The method of Example 4, wherein the stapling assembly includes a decksurface having a plurality of openings that house the staples, whereinthe predetermined longitudinal position of the staple driver membercomprises a position in which the crowns of the staples are positionedat the deck surface.

EXAMPLE 6

The method of any of the preceding Examples, wherein the staple drivermember is actuatable distally through a stapling stroke, wherein theknife member is actuatable distally through a cutting stroke, whereincontrolling the motor unit to initiate actuation of the knife membercomprises initiating the cutting stroke before completion of thestapling stroke.

EXAMPLE 7

The method of any of the preceding Examples, wherein the staplingassembly includes a sensor in communication with the controller, whereinthe method further comprises controlling actuation of at least one ofthe closure member, the staple driver member, or the knife member inresponse to a signal provided to the controller by the sensor.

EXAMPLE 8

The method of Example 7, wherein the method further comprises detectingwith the sensor that the staple driver member has reached thepredetermined longitudinal position.

EXAMPLE 9

The method of any of the preceding Examples, wherein the method furthercomprises detecting with the sensor that the tissue gap indicated by theuser input has been achieved by the stapling assembly.

EXAMPLE 10

The method of any of the preceding Examples, wherein the staplingassembly includes a current sensor operatively coupled with the motorunit and the controller, wherein the method further comprisescontrolling a rate of actuation of at least one of the closure member,the staple driver member, or the knife member based on a signal providedby the current sensor, wherein the signal indicates an electricalcurrent drawn by the motor unit.

EXAMPLE 11

The method of Example 10, wherein controlling the rate of actuationbased on the signal provided by the current sensor includes decreasingthe rate of actuation in response to detection by the current sensor ofan increase in electrical current drawn by the motor unit.

EXAMPLE 12

The method of any of the preceding Examples, further comprisingcontrolling a longitudinal displacement of at least one of the closuremember, the staple driver member, or the knife member based on the userinput.

EXAMPLE 13

The method of any of the preceding Examples, further comprisingcontrolling a rate of actuation of at least one of the closure member,the staple driver member, or the knife member based on the user input.

EXAMPLE 14

The method of any of the preceding Examples, wherein the controller isconfigured to store and execute a closure member actuation algorithm toactuate the closure member via the motor unit to transition the staplingassembly to the closed state, wherein the method further comprises: (a)while actuating the closure member from a first longitudinal position toa second longitudinal position, comparing with the controller an actuallongitudinal displacement of the closure member to an expectedlongitudinal displacement stored by the controller; (b) determining withthe controller that the actual longitudinal displacement differs fromthe expected longitudinal displacement by a difference value; and (c)adjusting the closure member actuation algorithm with the controllerbased on the difference value.

EXAMPLE 15

The method of any of the preceding Examples, wherein the controller isconfigured to store and execute a staple driver member actuationalgorithm to actuate the staple driver member longitudinally to drivethe staples into the clamped tissue, and a knife member actuationalgorithm to actuate the knife member longitudinally to cut the clampedtissue, wherein the method further comprises adjusting with thecontroller at least one of the staple driver member actuation algorithmor the knife member actuation algorithm based on the difference value.

EXAMPLE 16

A method of operating a powered surgical stapler having a motor unit, acontroller in communication with the motor unit, and a stapling assemblyoperatively coupled with the motor unit, wherein the stapling assemblyincludes a closure member, a staple driver member, a knife member, adeck surface having a plurality of staple openings, and a plurality ofstaples housed within the staple openings, wherein the stapling assemblyis actuatable between an open state for receiving tissue and a closedstate for clamping tissue, the method comprising: (a) receiving with thecontroller a user input that indicates a tissue gap to be defined by thestapling assembly in the closed state; (b) based on the user input,controlling the motor unit to actuate the closure member to transitionthe stapling assembly to the closed state to define the tissue gap andclamp tissue therein; (c) with the stapling assembly in the closedstate, controlling the motor unit to actuate the staple driver member todrive the staples from the staple openings into the clamped tissue; and(d) in response to the staples reaching a predetermined longitudinalposition relative to the deck surface, controlling the motor unit toinitiate actuation of the knife member to cut the clamped tissue.

EXAMPLE 17

The method of Example 16, wherein the stapling assembly includes asensor in communication with the controller, wherein the method furthercomprises detecting with the sensor that the staples have reached thepredetermined longitudinal position.

EXAMPLE 18

The method of any of Examples 16 through 17, further comprisingcontrolling at least one of a rate of actuation of the knife member or alongitudinal displacement of the knife member based on the user input.

EXAMPLE 19

A method of operating a powered surgical stapler having a motor unit, acontroller in communication with the motor unit, and a stapling assemblyoperatively coupled with the motor unit and having a closure member, astaple driver member, and a knife member, wherein the stapling assemblyis actuatable between an open state for receiving tissue and a closedstate for clamping tissue, the method comprising: (a) receiving with thecontroller a user input that indicates a tissue gap to be defined by thestapling assembly in the closed state; (b) based on the user input,controlling the motor unit to actuate the closure member to transitionthe stapling assembly to the closed state to define the tissue gap andclamp tissue therein; (c) with the stapling assembly in the closedstate, controlling the motor unit to actuate the staple driver member todrive staples into the clamped tissue; and (d) after initiatingactuation of the staple driver member, controlling the motor unit basedon the user input to actuate the knife member to cut the clamped tissue.

EXAMPLE 20

The method of Example 19, wherein controlling the motor unit based onthe user input to actuate the knife member comprises controlling atleast one of a longitudinal displacement or a rate of actuation of theknife member based on the user input.

VII. Miscellaneous

It should also be understood that any one or more of the teachings,expressions, embodiments, examples, etc. described herein may becombined with any one or more of the other teachings, expressions,embodiments, examples, etc. that are described herein. Theabove-described teachings, expressions, embodiments, examples, etc.should therefore not be viewed in isolation relative to each other.Various suitable ways in which the teachings herein may be combined willbe readily apparent to those of ordinary skill in the art in view of theteachings herein. Such modifications and variations are intended to beincluded within the scope of the claims.

Furthermore, any one or more of the teachings herein may be combinedwith any one or more of the teachings disclosed in U.S. Pat. App. No.[Atty. Ref. END9128USNP1], entitled “Method for Calibrating Movements ofActuated Members of Powered Surgical Stapler,” filed on even dateherewith; U.S. Pat. App. No. [Atty. Ref. END9130USNP1], entitled “Methodfor Controlling End Effector Closure for Powered Surgical Stapler,”filed on even date herewith; and U.S. Pat. App. No. [Atty. Ref.END9142USNP1], entitled “Anvil Retention and Release Features forPowered Circular Surgical Stapler,” filed on even date herewith. Thedisclosure of each of these U.S. patent applications is incorporated byreference herein.

It should be appreciated that any patent, publication, or otherdisclosure material, in whole or in part, that is said to beincorporated by reference herein is incorporated herein only to theextent that the incorporated material does not conflict with existingdefinitions, statements, or other disclosure material set forth in thisdisclosure. As such, and to the extent necessary, the disclosure asexplicitly set forth herein supersedes any conflicting materialincorporated herein by reference. Any material, or portion thereof, thatis said to be incorporated by reference herein, but which conflicts withexisting definitions, statements, or other disclosure material set forthherein will only be incorporated to the extent that no conflict arisesbetween that incorporated material and the existing disclosure material.

Versions of the devices described above may have application inconventional medical treatments and procedures conducted by a medicalprofessional, as well as application in robotic-assisted medicaltreatments and procedures. By way of example only, various teachingsherein may be readily incorporated into a robotic surgical system suchas the DAVINCI™ system by Intuitive Surgical, Inc., of Sunnyvale, Calif.

Versions described above may be designed to be disposed of after asingle use, or they can be designed to be used multiple times. Versionsmay, in either or both cases, be reconditioned for reuse after at leastone use. Reconditioning may include any combination of the steps ofdisassembly of the device, followed by cleaning or replacement ofparticular pieces, and subsequent reassembly. In particular, someversions of the device may be disassembled, and any number of theparticular pieces or parts of the device may be selectively replaced orremoved in any combination. Upon cleaning and/or replacement ofparticular parts, some versions of the device may be reassembled forsubsequent use either at a reconditioning facility, or by a userimmediately prior to a procedure. Those skilled in the art willappreciate that reconditioning of a device may utilize a variety oftechniques for disassembly, cleaning/replacement, and reassembly. Use ofsuch techniques, and the resulting reconditioned device, are all withinthe scope of the present application.

By way of example only, versions described herein may be sterilizedbefore and/or after a procedure. In one sterilization technique, thedevice is placed in a closed and sealed container, such as a plastic orTYVEK bag. The container and device may then be placed in a field ofradiation that can penetrate the container, such as gamma radiation,x-rays, or high-energy electrons. The radiation may kill bacteria on thedevice and in the container. The sterilized device may then be stored inthe sterile container for later use. A device may also be sterilizedusing any other technique known in the art, including but not limited tobeta or gamma radiation, ethylene oxide, or steam.

Having shown and described various embodiments of the present invention,further adaptations of the methods and systems described herein may beaccomplished by appropriate modifications by one of ordinary skill inthe art without departing from the scope of the present invention.Several of such potential modifications have been mentioned, and otherswill be apparent to those skilled in the art. For instance, theexamples, embodiments, geometrics, materials, dimensions, ratios, steps,and the like discussed above are illustrative and are not required.Accordingly, the scope of the present invention should be considered interms of the following claims and is understood not to be limited to thedetails of structure and operation shown and described in thespecification and drawings.

I/We claim:
 1. A method of operating a powered surgical stapler having amotor unit, a controller in communication with the motor unit, and astapling assembly operatively coupled with the motor unit and having aclosure member, a staple driver member, and a knife member, wherein thestapling assembly is actuatable between an open state for receivingtissue and a closed state for clamping tissue, the method comprising:(a) receiving with the controller a user input that indicates a tissuegap to be defined by the stapling assembly in the closed state; (b)based on the user input, controlling the motor unit to actuate theclosure member to transition the stapling assembly to the closed stateto define the tissue gap and clamp tissue therein; (c) with the staplingassembly in the closed state, controlling the motor unit to actuate thestaple driver member to drive staples into the clamped tissue; (d) afterinitiating actuation of the staple driver member, determining with thecontroller that the staple driver member has reached a predeterminedlongitudinal position; and (e) in response to the determination,controlling the motor unit to initiate actuation of the knife member tocut the clamped tissue.
 2. The method of claim 1, wherein the closuremember, the staple driver member, and the knife member are actuatable bythe motor unit independently of one another.
 3. The method of claim 1,wherein actuating the staple driver member to drive staples into theclamped tissue and actuating the knife member to cut the clamped tissuecomprise actuating the staple driver member and the knife memberdistally relative to the motor unit.
 4. The method of claim 1, whereinthe stapling assembly includes an anvil, wherein each staple includes acrown and a pair of legs, wherein the predetermined longitudinalposition of the staple driver member comprises a position in which thelegs have been at least partially deformed by the anvil.
 5. The methodof claim 4, wherein the stapling assembly includes a deck surface havinga plurality of openings that house the staples, wherein thepredetermined longitudinal position of the staple driver membercomprises a position in which the crowns of the staples are positionedat the deck surface.
 6. The method of claim 1, wherein the staple drivermember is actuatable distally through a stapling stroke, wherein theknife member is actuatable distally through a cutting stroke, whereincontrolling the motor unit to initiate actuation of the knife membercomprises initiating the cutting stroke before completion of thestapling stroke.
 7. The method of claim 1, wherein the stapling assemblyincludes a sensor in communication with the controller, wherein themethod further comprises controlling actuation of at least one of theclosure member, the staple driver member, or the knife member inresponse to a signal provided to the controller by the sensor.
 8. Themethod of claim 7, wherein the method further comprises detecting withthe sensor that the staple driver member has reached the predeterminedlongitudinal position.
 9. The method of claim 7, wherein the methodfurther comprises detecting with the sensor that the tissue gapindicated by the user input has been achieved by the stapling assembly.10. The method of claim 1, wherein the stapling assembly includes acurrent sensor operatively coupled with the motor unit and thecontroller, wherein the method further comprises controlling a rate ofactuation of at least one of the closure member, the staple drivermember, or the knife member based on a signal provided by the currentsensor, wherein the signal indicates an electrical current drawn by themotor unit.
 11. The method of claim 10, wherein controlling the rate ofactuation based on the signal provided by the current sensor includesdecreasing the rate of actuation in response to detection by the currentsensor of an increase in electrical current drawn by the motor unit. 12.The method of claim 1, further comprising controlling a longitudinaldisplacement of at least one of the closure member, the staple drivermember, or the knife member based on the user input.
 13. The method ofclaim 1, further comprising controlling a rate of actuation of at leastone of the closure member, the staple driver member, or the knife memberbased on the user input.
 14. The method of claim 1, wherein thecontroller is configured to store and execute a closure member actuationalgorithm to actuate the closure member via the motor unit to transitionthe stapling assembly to the closed state, wherein the method furthercomprises: (a) while actuating the closure member from a firstlongitudinal position to a second longitudinal position, comparing withthe controller an actual longitudinal displacement of the closure memberto an expected longitudinal displacement stored by the controller; (b)determining with the controller that the actual longitudinaldisplacement differs from the expected longitudinal displacement by adifference value; and (c) adjusting the closure member actuationalgorithm with the controller based on the difference value.
 15. Themethod of claim 14, wherein the controller is configured to store andexecute a staple driver member actuation algorithm to actuate the stapledriver member longitudinally to drive the staples into the clampedtissue, and a knife member actuation algorithm to actuate the knifemember longitudinally to cut the clamped tissue, wherein the methodfurther comprises adjusting with the controller at least one of thestaple driver member actuation algorithm or the knife member actuationalgorithm based on the difference value.
 16. A method of operating apowered surgical stapler having a motor unit, a controller incommunication with the motor unit, and a stapling assembly operativelycoupled with the motor unit, wherein the stapling assembly includes aclosure member, a staple driver member, a knife member, a deck surfacehaving a plurality of staple openings, and a plurality of staples housedwithin the staple openings, wherein the stapling assembly is actuatablebetween an open state for receiving tissue and a closed state forclamping tissue, the method comprising: (a) receiving with thecontroller a user input that indicates a tissue gap to be defined by thestapling assembly in the closed state; (b) based on the user input,controlling the motor unit to actuate the closure member to transitionthe stapling assembly to the closed state to define the tissue gap andclamp tissue therein; (c) with the stapling assembly in the closedstate, controlling the motor unit to actuate the staple driver member todrive the staples from the staple openings into the clamped tissue; and(d) in response to the staples reaching a predetermined longitudinalposition relative to the deck surface, controlling the motor unit toinitiate actuation of the knife member to cut the clamped tissue. 17.The method of claim 16, wherein the stapling assembly includes a sensorin communication with the controller, wherein the method furthercomprises detecting with the sensor that the staples have reached thepredetermined longitudinal position.
 18. The method of claim 16, furthercomprising controlling at least one of a rate of actuation of the knifemember or a longitudinal displacement of the knife member based on theuser input.
 19. A method of operating a powered surgical stapler havinga motor unit, a controller in communication with the motor unit, and astapling assembly operatively coupled with the motor unit and having aclosure member, a staple driver member, and a knife member, wherein thestapling assembly is actuatable between an open state for receivingtissue and a closed state for clamping tissue, the method comprising:(a) receiving with the controller a user input that indicates a tissuegap to be defined by the stapling assembly in the closed state; (b)based on the user input, controlling the motor unit to actuate theclosure member to transition the stapling assembly to the closed stateto define the tissue gap and clamp tissue therein; (c) with the staplingassembly in the closed state, controlling the motor unit to actuate thestaple driver member to drive staples into the clamped tissue; and (d)after initiating actuation of the staple driver member, controlling themotor unit based on the user input to actuate the knife member to cutthe clamped tissue.
 20. The method of claim 19, wherein controlling themotor unit based on the user input to actuate the knife member comprisescontrolling at least one of a longitudinal displacement or a rate ofactuation of the knife member based on the user input.